The oxidative hydrodimerisation (OHD) of propene has been chosen to study the catalytic behaviour of BIMEVOX oxides which present a remarkable ionic conductivity by O2-. The catalytic experiments performed with Bi2Cu0.1 V0.9O5.35 (BICU-VOX) and Bi2Co0.1 V0.9O5.35 (BICOVOX) show that their behaviour is unusual: the total oxidation of propene to COx which proceeds at low temperature (up to 450degreesC) is partly replaced by its oxidative dimerisation to 1,5-hexadiene (HXD) at higher temperature. EPR and TPD experiments mainly used to follow the evolution of catalysts with temperature under conditions close to those of catalytic tests show that the redox V5+/V4+ operates at high temperature and is responsible for the formation of 1,5-hexadiene. (C) 2003 Elsevier B.V. All rights reserved.