Polymer-supported oxidising agents are very useful in organic synthesis, due to easy recovery and regeneration. The selective formation of benzaldehyde from benzyl chloride by using chromate salts supported on a polystyrene matrix crosslinked with divinylbenzene containing a quaternary functional group has been investigated in detail. The effects of various parameters on the rates of reaction have been studied. The mechanism and kinetics of this reaction have been established. There is a total selectivity for benzaldehyde and the reduced chromate species can be regenerated. The results are novel.