Phenolic compounds are widely present in plant kingdom and thus are common components of the human diet, generally found in both edible and inedible plants. These are chemically complex substances consisting of an aromatic ring which contain one or more hydroxyl substituents and their structures may range from a simple phenolic molecule to that of a complex high-molecular mass polymer including phenolic acids, coumarins, tannins and flavonoids. They show a wide range of biological activities such as anti-oxidant, anti-viral, anti-allergic, cardioprotective, anti-carcinogenic, anti-inflammation, anti-estrogen etc. Due to these health benefits and the steady progress of medicinal sciences, analytical techniques for their characterization and quantification are required. Several methods for the determination of phenolic compounds have been described in the literature. But most of these methods have limited resolution, low sensitivity and require long time for analysis. Capillary electrophoresis (CE) offer several advantages over other methods because of its extremely high efficiency, small sample volume, high speed, and good resolution. Reversed-phase high performance liquid chromatography (RP-HPLC) is also the most commonly used analytical technique for the analysis of phenolic compounds as it does not require derivatization prior to analysis. In our present study, five methods have been developed for the determination of phenolic compounds from biological samples (human blood serum) and some natural samples (fruits, vegetables, herbs and spices). First study describes the development of a micellar electrokinetic chromatography (MEKC) method for the determination of naringenin in real samples including citrus fruit juices and human blood serum, using photodiode array (PDA) detector. The effects of several CE parameters including concentration and pH of the running buffer, voltage, injection time and concentration of sodium dodecyl sulfate (SDS) were optimized. Under the optimum conditions, naringenin could be well determined within 6 minutes in a 40mM borate buffer containing 40mM SDS at pH 9.0 and an applied voltage of 25 KV. For the quantitative determination of naringenin (flavonoid aglycone) in juice samples, the naringin (flavonoid glycoside) was hydrolysed and the resulting aglycone was identified and quantified. The calibration curve was linear in the studied concentration range from 0.1 to 50 µg/ml (R2=0.995). The detection limit and limit of quantification was found to be 0.05 and 0.19 µg/ml, respectively. The second method describes the development and validation of a fast capillary zone electrophoretic (CZE) method for determination of quercetin, rutin, naringin and naringenin in various fruits, such as Apples (Malus domestica), Oranges (Citrus sinenis), Grapefruits (Citrus paradisi) and Ber (Ziziphus mauritiana L.) using photodiode array (PDA) detector. Under the optimum conditions, all four flavonoids were well determined in a 10 mM borate buffer of pH 8.5 within 10 min, while applied voltage was 25 kV. Naringin, naringenin and quercetin were found to have linear response in the range of 3.12-200 µg/mL where as rutin’s response was linear from 6.25 µg/mL to 200 µg/mL. LOD of naringin, naringenin, rutin and quercetin was found to be 0.406, 0.314, 0.582 and 0.333 µg/mL, respectively and LOQ of naringin, naringenin, rutin and quercetin was found to be 1.355, 1.046, 1.941 and 1.11, respectively. Long term stability and good reproducibility of developed method is evident from values of relative standard deviations (RSD) which were less than 3% for both migration time and peak height. Third method describes the development and validation of a fast, effective and reliable capillary zone electrophoresis (CZE) method for the determination of five flavonoids (epicatechin, epigallocatechin gallate, chrysin, morin and hesperedin) using 1-butyl-3-methyl imidazolium ionic liquid (IL) as a buffer additive. The effects of several CE parameters including concentration and pH of the running buffer, voltage and concentration of ionic liquid were optimized. Under optimized conditions, all five analytes were well determined within 12 min in a 25 mM borate buffer (pH 9) at an applied voltage of 15 kV and 10 µL of IL was added in the buffer. Validation of the method was performed in terms of linearity, accuracy, VII precision and limit of detection and quantification. The linearity of the calibration curves for 6.25 to 200 µg/mL for EC and chrysin, 12.5 to 200 µg/mL for EGCG and morin, whereas 1.56 to 200 µg/mL for hespiridin. The response was linear with coefficient of determination (R2) = 0.990 for EC, hespiridn and chrysin, 0.992 for morin and 0.988 for EGCG. LOD and LOQ were obtained within 0.4 - 0.5 µg/mL and 1.4 - 1.7 µg/mL, respectively. The proposed method demonstrated good long reproducibility with relative standard deviations (RSD) of less than 3% for both migration time and peak height (n= 5 for intra day and n=3 for inter day ). The developed method was successfully applied on real samples such as green tea, black tea and honey. Fourth study describes the development and validationof capillary electrophoresis method with large volume sample stacking (CE-LVSS) and for the simultaneous determination of seven phenolic compounds namely, naringin, rutin, carnosic acid, apigenin, quercetin, morin and chichoric acid. Optimization was carried out by response surface methodology and set of 20 experiments helped to optimize the parameters such as concentration of buffer, pH of buffer and applied voltage. Analytes were separated on capillary of 50 µm diameter and 56 cm effective length with extended light path using 20 mM borate buffer of pH 9.2. LVSS method was optimized and 3 to 5 fold improvement in detectability was achieved with injection at 100 mbar for 20 s followed by polarity switching at -20 kV for 6 s. Linearity of all seven analytes were observed in the concentration ranges of0.5-50 µg/mL for CZE and 0.1-25 µg/mL for LVSS. LODs were obtained within 0.012 to 0.241 and 0.003 to 0.086 µg/mL, for CZE and LVSS, respectively, whereas LOQs were obtained within 0.041 to 0.802 for CZE and 0.012 to 0.286 µg/mL for LVSS. Recoveries were found to be in the range of 91.1109.8% and 96.3-108.4%for CZE and LVSS, respectively. The developed method has been successfully applied for the quantitative determination of analysed components from different food samples which are important sources of these compounds. Fifth study describes the development and validation of a reverse phase high performance liquid chromatography (RP-HPLC) coupled with DAD detector for the simultaneous determination of five phenolic compounds namely, rutin, VIII naringin, morin, quercetin and p-coumaric acid. Optimization was carried out by using Taguchi experimental design. Set of 32 experiments helped to optimize the parameters such as pH, concentration and percentage of buffer and temperature of the column. Analytes were separated on C8 column within 19 min using isocratic system of 0.1% phosphoric acid and acetonitrile (75: 25 v/v) as mobile phase with flow rate of 0.1 mL/min. Lineartiy of all five analytes were observed in the concentration ranges of 0.5-70 µg/mL. Limit of detection (LOD) and limit of quantification (LOQ) were found to be in the range of 0.024 to 0.081 and 0.081 to 0.269 µg/mL, respectively. Recoveries and relative standard deviations (%RSD) were found to be in the range of 96.7-105.3% and 0.05-1.68%, respectively. The developed method has been successfully applied for the quantitative determination of analysed components from different food samples which are important sources of these compounds.