Abstract: A catalyst composition for preparing acrylic acid from acrolein, comprising a catalytic oxide on an inert porous carrier, said catalytic oxide having the composition of the formulaMo.sub.a V.sub.b Z.sub.c W.sub.d Cu.sub.eWherein Z is at least one alkaline earth metal atom selected from the group consisting of beryllium, magnesium, calcium, barium and strontium; a, b, c, d, and e are the numbers of the respective metal atoms; when a is 12, b is 2 to 14, c is 0.1 to 6, d is 0 to 12, and e is 0 to 6, with the proviso that d plus e is not 0,And a process for preparing acrylic acid by the catalytic vapor-phase oxidation of acrolein with a gas containing molecular oxygen in the presence of such catalyst.