A process for the production of iohexol comprises alkylating 5-Acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide using 2(2-methoxy-ethoxy)-ethanol as solvent in the presence of a base, and optionally isolating crude iohexol from the reaction mixture. Preferably, the alkylating agent is 1-chloro-2,3 propanediol and the base is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.