An amperometric non-enzymatic sensor based on Pt-Au-organosilica chitosan (Pt-Au-osioCS) com- posites has been developed for determining catechol (CC, 12-dihydroxybenzene) and hydroquinone (HQ, 14-dihydroxybenzene). The Pt-Au-osiocs composites were synthesized using positively charged inorganic-organic core-shell organosilicaechitosan (osiocs) crosslinked nanospheres as templates for the assembly of negatively charged 1-3 nm Au nanoparticles seeds which acted in subsequent step as nucleation sites for the reduction of platinum. Due to the excellent electrocatalytic response of Pt- Au-osiocs for the reduction of CC and HQ, the sensor based on the Pt-Au-osiocs exhibited broad linear range of 0.06-90.98 uM for CC and 003-172.98 uM for HQ. The low detection limits of 0.02 and 0.01 RM (SN a 3) were obtained for CC and HQ, respectively. The operational conditions were opti- mized. The sensitivities of the non-enzyme electrode for CCand HQ were 307.95 uAmM-1 cm-2 and 1714.20 Am M-1 cm respectively