Abstract Aluminium metal has been hydrolysed at 100 °C to synthesize boehmite. Gelatinous and dry boehmite were used to prepare stable sol. In the case of gelatinous boehmite, sol was prepared by peptizing and in the case of dry boehmite an ultrasonic bath was used to prepare the sol. Gelation was carried out by heating on a hot plate, which resulted in sol–gel processed powder. For sol–gel processed boehmite the θ→α transformation occurred at 1078 °C and for the as prepared boehmite the same occurred at 1206 °C. Sol–gel processed powder could be transformed to α alumina completely, when calcined at 1000 °C for 1 h.