Various supported precious metal (Pt, Rh, Ru, Ir) catalysts have been screened in the reduction of benzonitrile (BN), benzyl cyanide (BC) and 3-phenylpropionitrile (PPN) to benzylamine (BA), 2-phenylethylamine (PEA) and 3-phenylpropylamine (PPA), using our method for selective, heterogeneous, palladium-catalysed hydrogenation of nitriles to primary amines developed previously. A readily available platinum on carbon catalyst (10% Pt/C) afforded the best results obtaining complete conversion of nitriles, as well as comparatively high isolated yields (58–70%) and selectivities to primary amines (57–68%) under mild and optimized conditions [6 bar, 30 °C, two immiscible solvents (dichloromethane/water or toluene/water), acidic additives (NaH2PO4, (NH4)H2PO4 or H2SO4)]. Contrary to the typical high secondary amine selectivity of platinum, surprisingly, this Pt/C catalyst proved to be much more effective and selective in the formation of PEA and PPA than a Pd/C one applied earlier. To clear the divergences in the primary amine selectivity observed, quantum chemical calculations (DFT) were accomplished related to the adsorption interactions between the imine intermediates and platinum.