A microreactor with two chambers separated by a disc of catalyst has been made and included in a catalytic test with on-line analysis by gas chromatography. The oxidative dimerization of propene in benzene and hexadiene has been studied using a disc of Bi-La-O catalyst. The results show that conversion of propene is higher (45-70 mol.-%) than in conventional reactors with co-fed oxygen. The selectivity in 1,5-hexadiene and benzene is also higher because of a lower amount of CO2. The deactivation of the catalyst is examined.