Abstract: According to the present invention, 5-substituted resorcinols of the formula I ##STR1## wherein R.sub.1 represents a hydrocarbon radical, optionally unsubstituted or substituted by inert substituents, are prepared by reacting a carboxylic acid ester of the formula IIr.sub.1 -- c .tbd. c -- co -- o -- r.sub.2 (ii)wherein R.sub.2 represents a non-aromatically bound lower hydrocarbon radical, in the presence of an alkaline condensation agent, with a diester of 3-oxoglutaric acid of the formula IIIr.sub.3 --o--co--ch.sub.2 --co--ch.sub.2 --co--o--r.sub.4 (iii)wherein R.sub.3 and R.sub.4 represent non-aromatically bound lower hydrocarbon radicals; hydrolyzing the resulting dihydroxyisophthalic acid acid ester of the formula IV ##STR2## and decarboxylating the hydrolyzed product, a specific embodiment is the preparation of 5-pentylresorcinol.