Abstract Microwave oven drying of zirconium molybdate- 99Mo (Zr 99Mo) was investigated for preparing a gel generator for 99mTc and compared with an earlier method standardised by us using hot air for drying. With a microwave frequency of 2.45 GHz and power output of 385 W, 30 g ZrMo gel (i.e. 10 g Mo) could be satisfactorily dried for use in a generator in only 35 min compared to 16 h required in the hot air drying method. A maximum of 180 mCi 99Mo with a molybdenum content of ∼2 g per column (∼6 g of ZrMo gel) was used in the present study. The performance features of the 99mTc gel generator and the quality of pertechnetate eluate are comparable to that obtained by other well established conventional methods and thus satisfactory for medical use. The merits of reduced processing time and decay loss, apart from ease of handling a critical processing step, are the attractive features of the new method.