The work in this thesis describes the synthesis and characterization of phenoxy isobutyric acid derivatives and their biological screening which includes anti-bacterial, antioxidant, biofilm inhibition and mutagenic assay. First part of this research work consists of alkylation of substituted phenols to get 4-chlorophenoxy isobutyric acid (131) and 4bromophenoxy isobutyric acid (179). These acids were converted into 4-chlorophenoxy isobutyrate (132) and 4-bromophenoxy isobutyrate (180) followed by their hydrazinolysis to obtain 2-(4-chlorophenoxy)-2-methyl propane hydrazide (133) and 2-(4-bromophenoxy)-2methyl propane hydrazide (181).Condensation of these hydrazides 133 & 181.with substituted benzaldehyde and aromatic acetophenone yielded N’-benzylidine-2-(4-chlorophenoxy)-2ethylpropanehydrazides (155-178) and N’-benzylidine-2-(4-bromophenoxy)-2- methyl propane hydrazides (182-196) respectively. In another series, chalcones (110-130) were synthesized by Claisan condensation reaction. These chalcones were react with 2-(4-chlorophenoxy)-2-methylpropanehydrazide (133) in ethanol and acidic environment to yield a novel series of 2-(4-chlorophenoxy)-[1,diphenylallylidene]-2-methylpropanehydrazides. (134-154). In the second part, all the compounds were characterized by spectroscopic techniques like IR, NMR, mass spectrometry and X-ray crystallography. In third part, all the compounds were subjected to biological screening, which includes anti-bacterial, anti-oxidant, biofilm inhibition, and mutagenic assay and it was found that these compounds have a great potential to act actively in drug discovery.