Ionic liquids (ILs) have attracted considerable interest as a promising “green” substitute for organic solvents. Although, toxicity of some ILs is a cause for concern, recent studies have shown that the toxic interactions of ILs toward biological systems can be quite useful, particularly for antimicrobial applications. 1-n- alkyl-3-methylimidazolium (Cnmim), a popular class of ILs, has been shown to be toxic toward several classes of aquatic species and organisms. Interactions of ILs with the cellular membrane play a major role towards toxicity as well as antimicrobial applications. The fundamental mechanisms underlying the interactions between ILs and cells are not well studied nor completely understood. Our aim is to investigate effects of Cnmim( n=4, 8, 10) on the dynamical and phase behaviour of phospholipid membrane and its correlation with the cation chain length of the ILs.