Three types of new amphiphilic poly(quaternary ammonium) dendrimer catalysts were prepared from poly(propylene imine) generation-2 (PPI-G2)dendrimer with 3 types of alkyl halides having varied chain length. The C-H stretching at 2922 and 2853 cm(-1) and C-N+ stretching at 1108 cm(-1) confirmed the attachment of alkyl chains and generation of poly(quaternary ammonium) ions at the dendrimer surface. Their H-1 and C-13 NMR spectra also supported such confirmations. The hydrophobicity of these 3 poly(quaternary ammonium) based dendrimer catalysts was determined by the static water contact angle (theta). The catalyst derived from attachment of long alkyl chain viz., PPI-G2-(C16H33)(16) (CH3)(8)-N+Cl- showed an increased contact angle (77.5 theta) thus proving high hydrophobicity. Their catalytic activity was evaluated through reduction of citronellal under pseudo-first order condition at ambient temperature. The rate constant (k(obs)), of the catalyst containing medium length alkyl chain viz., PPI-G2-(C12H25)(16) (CH3)(8)-N+Cl- was higher than those containing short and long alkyl chains due to its well-balanced amphiphilic character. It gave 100% selectivity/activity compared to commercial single-site phase transfer catalyst for citronellal reduction. The effect of [substrate], [catalyst], [NaOH], and [NaBH4] on the rate of the reaction was studied and the results were discussed. (C) 2012 Elsevier B.V. All rights reserved.