To provide an improved catalyst carried on a polyoxomethalate salt for a variety of chemical processes.

A catalyst composition contains a catalyst deposited on a polyoxomethalate carrier having the general formula: CaH(e-az)(XkMm-xM1xM2nOy)-e (I) (wherein, C is a cation selected from potassium, rubidium and the like; X is an element selected from elements of groups 3-16; M is molybdenum or tungsten or their combination; M1 is vanadium; M2 is a transition metal different from M and M1; (z) is the valence of C; (k) is 1-5; (m) is 5-20; (n) is 0-3; (x) is 0-6; (y) is 18-62; and (e) is the valence of the polyoxomethalate anion). The catalyst is not a heteropolyacid.