This thesis is focused on understanding the nature of the perturbations on the structure and dynamics of water as induced by electrolytes (chlorides of alkali metals), amphiphilic molecules (DME, DMSO, alcohols etc.) and by hydrophobic ions (cations that contain hydrophobic moieties: alkylammonium chlorides). Most of the bio-physical processes in real cellular environments are governed by electrostatic and/or hydrophobic interactions. We investigate the individual as well as simultaneous effects of electrolytes and hydrophobic molecules on water network and dynamics. We have experimentally investigated the local Hbonded structure (using FTIR spectroscopy) and dynamics (using optical pump-probe spectroscopy) as well as the collective water networks along with the cooperative hydration dynamics (using GHz-THz spectroscopy). We have also implemented molecular dynamics simulation technique to get a icroscopic view of water structure and dynamics in presence of DME molecules. Form MD simulation study, we capture non-monotonic character in the single molecule water reorientation times. We found that there exist quite stable H-bonded water clusters in all simulated water concentration mixtures (even in very low water concentration). Water reorientations are found to occur via a combination of large amplitude angular jumps and diffusive motions. With the understanding of the perturbations on water networks, we studied the structure and hydration of a model protein bovine serum albumin (BSA) in presence of co-solutes and co-solvents. The change in the protein native structure has been determined using dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy techniques while the associated hydration dynamics is investigated with THz spectroscopy. We aim to mimic the real cellular environment as it contains hydrophilic, hydrophobic and ionic charged species simultaneously. We found that while the alkali metal cations do accelerate the collective dynamics of water, it hardly affects the protein structure and its hydration dynamics; salt hydration and the BSA hydration act independently of each other. On the other hand, alcohols and alkylammonium cations do perturb the protein structure significantly indicating that direct preferential hydrophobic interactions of these molecules accelerate protein denaturation processes. We found that there exist a delicate balance between direct and indirect interactions, where electrolytes prefer to interact indirectly and amphiphilic molecules perturbed with preferential hydrophobic interactions.