Abstract <p>A series of new <i>N</i>′-(9<i>H</i>-xanthen-9-yl)carbohydrazides have been synthesized by the reaction of alkanehydrazides and cyclohexanecarbohydrazide with 9<i>H</i>-xanthen-9-ol (xanthydrol) and pyridinium per­chlorate. Xanthydrol and pyridinium perchlorate form a stable complex, <i>N</i>-(9<i>H</i>-xanthen-9-yl)pyridinium perchlorate, the lability of the C⁹–N⁺ bond in which favors easy introduction of the heterocyclic fragment into carbohydrazides. Antioxidant evaluation of the synthesized compounds revealed their antioxidant activity in the range of 0.62 to 0.73 relative units (with respect to ascorbic acid). Elongation of the alkyl chain of linear <i>N</i>′-(9<i>H</i>-xanthen-9-yl)alkanehydrazides increased their antioxidant activity, whereas branching of the alkyl fragment significantly reduced the antioxidant effect or did not affect it.</p>