The invention relates to a method for preparing acrylic acid from propylene, comprising the oxidation of propylene to acrolein and a second step comprising the oxidation of acrolein to acrylic acid, including a glycerol dehydration step preformed in the presence of a gas containing propylene and, more specifically, in the presence of the reaction gas originating from the propylene to acrolein oxidation step. The inventive method enables the use, in part, of renewable raw material, while increasing acrylic acid production.