PURPOSE: To selectively produce a corresponding org. acid by bringing 3 to 10C aliphat. alcohol and O2 into reaction in a contact state by using a calcined oxide catalyst contg. Mo and V metals alone or at least one kind of other metals as a catalyst.

CONSTITUTION: The 3 to 10C aliphat. alcohol (e.g. ethanol, etc.) and the oxygen are brought into reaction in the gaseous phase at 75 to 500°C and under a 1 to 75 atm in the presence of the calcined oxide catalyst of formula (Z denotes nothing or ≥1 kinds among Nb, Sb, Li, Se, Na, Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, Y, Ta, Cr, Fe, Co, Ni, Ce, La, Zn, Cd, Hg, Al, Tl, Pb, As, Bi, The, U and W; (x) is 0.5 to 0.9; (y) is 0.1 to 0.4 and (z) is 0 to 1), by which the corresponding acid (e.g. acetic acid, etc.), is obtd. Acetic acid plus ethylene is obtd. by the catalytic oxidation of a mixture composed of ethanol and ethane by this process.