Activated carbon from agro waste groundnut (Arachis hypogaea) shell was prepared by chemical activation and used as support for dispersion of 5% platinum nanoparticles. The Pt nanoparticles were obtained by the reduction in hydrogen gas medium. The synthesized groundnut activated carbon/platinum catalyst was characterized by various techniques such as X-ray powder diffraction, electron microscopies and X-ray photoelectron spectroscopy. The catalytic behaviour of the synthesized catalyst was investigated by exploring it as catalyst for the reduction of various classes of dyes; namely, triphenylmethane dyes such as malachite green, phenol red and bromophenol blue, xanthene dyes: rose bengal, rhodamine 6 G, rhodamine B, thiazine dye: methyelene blue, azo dye: congo red and 4-nitrophenol by sodium borohydride in aqueous medium. Under suitable reaction conditions, for all tested dyes, cationic dyes were reduced at a faster rate than anionic dyes. The rate of reduction on the structure of dye and nature of catalyst was employed. © 2018 Elsevier B.V.