Catalytic properties of the binary phosphorus-molybdenum system with M
o/P = 3 - 24.5 in acrolein oxidation have been studied. The selectivit
y to acrylic acid and carbon oxides practically does not depend on the
chemical composition of the system, and the maximum activity is obser
ved for Mo/P = 12. The catalytic properties of the system are determin
ed by an X-ray amorphous phase, apparently molybdenyl phosphate.