The supported Mo catalysts were pretreated using hydrofluoric acid. Then Mo was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES). In the present method, the detection limit of Mo was 8.220 ng x mL(-1), the recovery of standard addition was 102.6%-104.3%, the relative standard deviation (n = 11) was less than 0.860%. The method is efficient, accurate, and easy to operate. Molybdenum in supported catalysts, which were prepared under different conditions, was determined by this method. The results showed that the content of Mo in supported catalysts decreased after preparation. The decreases in the content of Mo were different when the active component concentrations in impregnation solution, and the calcination temperature, changed.