Particularly, acrylic acid, acrylonitrile and their derivatives in available polyhydroxyalkanoic a

A catalyst for the selective oxidation and amoxidation of alkanes and/or alkenes, particularly in processes for obtaining acrylic acid, acrylonitrile and derivatives of these, including a least one oxide of Mo, Te, V, Cu and at least another A component selected from among Nb, Ta, Sn, Se, W, Ti, Fe, Co, Ni, Cr, Ga, Sb, Bi, a rare, alkaline or alkali-earth earth, in such a way that the catalyst presents, in a calcined form, an X-ray diffractogram with five intensive diffraction lines, typically the most intense corresponding to diffraction angles of 2θ at 22.1+/-0.4, 27.1+/-0.4; 28.1+/-0.4, 36.0+/-0.4 and 45.1+/-0.4. In the preferred embodiment, the catalyst has the following empiric formula : MoTehViCujAkOx in which h, i, j, k are values comprised between 0.001 and 4.0 and x depends on the oxidation status or valency of the Mo, Te, V, Cu and A elements.