Catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, wherein an alkene and carbon dioxide are reacted in the presence of a carboxylation catalyst and in the presence of a specific aryloxide to obtain the α,β-ethylenically unsaturated carboxylic acid salt, the carboxylation catalyst being a transition metal complex. The process allows for efficient preparation of α,β-ethylenically unsaturated carboxylic acid derivatives from CO2 and an alkene.