This dissertation study aims to the investigation of new biosorbent from locally available low cost agriculture material, rice husk, for scavenging of heavy metals especially precious and rare earth metals. Rice husk was treated with NaOH solution to check the effect of modification on metal ions adsorption. Rice husks treated and virgin were characterized by Fourier transform infrared (FT-IR) spectrometry, Scanning Electron Microscopy (SEM), Energy dispersive X- Ray (EDX) and Brunner EmmetTeller (BET) techniques. The rice husk (RH) & NaOH treated rice husk (TRH) were characterized by various physico-chemical methods like porosity, bulk density, ash, volatile and moisture contents, pHPZC, pH and methylene blue surface area measurements. The determined surface area of RH was 47.91 and TRH was 272.06 m2 g−1 by methylene blue method whereas BET surface area was 1.03 for RH and 2.53 m2g−1 for TRH. From the comparison of FTIR spectra of RH and TRH and metals loaded adsorbent, it was found that metals ions mostly attached with the oxygen and silicon containing functional groupsThus OH, −COOH, O CH3 and Si−O−Si, functional groups play vital role in the adsorptive removal of heavy metals ions from aqueous solutions. SEM analysis showed that RH and TRH possess rough and porous structures and the morphological difference between them revealed that the NaOH treatment created large and wide pores making TRH more rough and porous material. The pore size for untreated rice husk was 100-108 nm and for treated rice husk was 355.57 to 1220 nm confirming macro porous structure of the adsorbent. SEM exhibited the morphological changes on the adsorbent surface after metal ions adsorption and were confirmed by EDX analysis by the presences of these metal ions on the adsorbent surface. Various physico-chemical parameters such as pH, mineral acid concentrations (HNO3, HCl, H2SO4 and HClO4), amount of adsorbent, contact time, initial metal ions concentration and temperature have been optimized for maximum removal of metal ions from aqueous media by rice husk employing batch mode. The removal of metal ions were quantitative within a short contact time of 10 - 25 minutes for all metal ions (Ag, Cs, Cu, Co, Ni, Th, La and Ce). Maximum adsorption of silver and cerium was observed in 1 × 10-2 mol L-1 of nitric acid solution whereas maximum adsorption in case of thorium, nickel, lanthanum and caesium was found in 1 × 10-2 mol L-1 nitric acid solution. The adsorption data obtained by the variation of equilibrium time was applied to various kinetic models. Pseudo second order was the best fitted kinetic model for the adsorption of precious and rare earth metal ions. Mechanism of metal ions uptake was verified by applying intra-particle, liquid film and Elovich models. The adsorption data of metal ions on rice husk obeyed the Freundlich, Langmuir and Dubinin-Radushkevich isotherm equations. Adsorption capacities of rice husk for all these metal ions were calculated form their linear and nonlinear forms. Regression coefficient ‗R2‘ and Chi square test ‗χ2‘ were used as the criteria for the best fit of adsorption isotherm models. The adsorption capacities of the rice husk obtained by the Freundlich isotherm were compared with the reported adsorption capacities of various adsorbents and rice husk was found better adsorbent for the removal of these metal ions from aqueous media. The sorption free energies determined by D-R isotherm confirmed chemisorption type of adsorption of metal ions on rice husk having numerical values in a range of 10.16 – 22.43 kJ mol−1 for the metal ions in this study. The adsorption processes were found to be endothermic in nature with positive values of ∆H in a range of 3 839 – 31.016 kJ mol−1 and ∆S values (16 839 – 115.764 J mol−1 K−1) confirmed increase in randomness at the solid-solution interface by the fixation of metal ions on the rice husk. The increased numerical values of ∆G with rise in temperature indicates that the adsorption process of metal ions ( Cu, Co, Ag, Ni, Cs, Th, La and Ce) on rice husk becomes more favourable at higher temperatures. Sticking probabilities and activation energies of all metal ions system favour the chemisorption nature of interactions with rice husk. The adsorption of metal ions occurs in the presence of a variety of anions and cations. Regeneration of adsorbent and recovery of metal ions were performed by using different concentrations of nitric acid. The developed procedures were successfully applied to the spiked tap water samples by removing the metal ions under optimized conditions. The maximum metal ions removal was obtained in two steps under optimized conditions. On the basis of this study it was concluded that abundantly and locally available inexpensive rice husk has great potential to be utilized for the removal of precious and rare earth metal ions from bulk aqueous solutions for the safe disposal of industrial as well as radioactive effluents and will provide an alternative solution to minimize environmental damages caused by these metal ions.