The present invention relates to hydroxymethylfurazancarboxylic acid derivatives of the general formula I ##STR1## in which one of the radicals R.sup.1 and R.sup.2 represents hydroxymethyl and the other represents ##STR2## where X represents NR.sup.3 R.sup.4, OH or OR.sup.7, and R.sup.3, R.sup.4 and R.sup.7 are defined as indicated in claim 1, to processes for their preparation and to their use.