The diazoimine/triazole equilibria of diazo substituted azoles are not well documented in the literature. Data have been reported for thiazoles,1.* thiadiazoles, 1 thiatriazoles3 and tetrazoles.4 but no information is available for oxazoles and oxadiazoles. In this investigation we wanted to fill this gap by considering some diazo derivatives of the title compounds.The diazoacyl substituted azoles 1 (281, mp 85°C from CHC13/Et20), 2 (65%, mp 58°C from CHCI,/Et20), 3 (36%, mp 71°C from EtOH) and 4 (48%, mp 142°C from CHCI,/Et20) were prepared I3C NMR spectrum (DMSO-d6). The triazole form 8 was not observed. Ph J 8 CONHPh L 7