A Process for preparing carboxylic esters of a mixture of structurally branched C9 monocarboxylic acids proceeding from 2-ethylhexanol is characterized in that (a) 2-ethylhexanol is dehydrated to an octene mixture in the presence of a catalyst; (b) the octene mixture obtained in step a) is reacted in the presence of a transition metal compound of group VIII of the periodic table of the elements with carbon monoxide and hydrogen to give a mixture of isomeric isononanals; (c) the mixture of isomeric isononanals obtained in step b) is oxidized to a mixture of structurally branched C9 monocarboxylic acids; and (d) the mixture of structurally branched C9 monocarboxylic acids obtained in step c) is reacted with alcohols to give carboxylic esters.