Poly(ionic liquids)(PILs) of the types poly(1-vinyl-3-alkyl imidazolium)X (where alkyl = ethyl, butyl & pentyl; X = Br- or OH-) are synthesized and used for the preparation of stable silver, gold and nickel nanoparticles in solution. Studies pertaining to the dispersion of metal NP stabilized by PILs are discussed. The role of PILs is prominent as carriers towards reversible "solubility switch" of synthesized metal nanoparticles between aqueous and organic media by simple anionic metathesis. These PIL stabilized nanoparticles show great stability for longer period without agglomeration. At another role of employed PIL is the ability to tune the size of the metal NP, depending on the length of alkyl chains of PIL. UV-Visible, SEM and TEM techniques are used for the characterization and morphological study. PIL stabilized Ag NP shows very good antimicrobial activity at lower concentrations against Escherichia coli and Staphylococcus aureus. Ag NP are used in the catalytic reduction of aromatic nitro compounds with NaBH4 and that of Ni NP for hydrogen transfer reduction of acetophenone in quantitative yields. © 2014 Elsevier Ltd. All rights reserved.