A process for producing acrylic acid in a high space-time yield

In a process for production of acrylic acid bringing a reaction gas comprising a gaseous source of formaldehyde and gaseous acetic acid, and wherein the partial pressure of the source of formaldehyde, calculated as formaldehyde equivalents, is at least 85 mbar, and in which the molar ratio of acetic acid to formaldehyde source, calculated as formaldehyde equivalents, is at least 1, in contact with a solid condensation catalyst. The space-time yield can be significantly increased by increasing the partial pressure of the reactants. The space-time yield remains high even after a long duration of proceedings.