Abstract: A new process is described for the preparation of oxalic acid esters and amides of general formula (I) ##STR1## wherein Z designates an --OR or --NR.sup.1 R.sup.2 group, wherein R represents substituted or unsubstituted alkyl, alkenyl, cycloalkyl, aryl, or aryl-alkyl, R.sup.1 is hydrogen or substituted or unsubstituted alkyl, alkenyl, cycloalkyl, aryl, or aryl-alkyl, R.sup.2 represents substituted or unsubstituted alkyl, alkenyl, cycloalkyl, aryl, or aryl-alkyl, or R.sup.1 and R.sup.2 taken together with the adjacent nitrogen atom represent a saturated 5-, 6-, 7-, or 8-membered heterocyclic ring, which may contain an additional heteroatom selected from --O--, --S--, and --N(H, Alkyl)--, and optionally bear one or more alkyl or alkenyl substituents, andZ.sup.1 designates an --OR or --NR.sup.1 R.sup.2 group, wherein R, R.sup.1, and R.sup.2 are as defined before, or a group --NHCOCH.sub.3, which comprises the base-catalysed reaction of diacetyloxamide with an alcohol ROH or/and an amine HNR.sup.1 R.sup.2.