Synthesis and characterization of a series of dialkyl esters of 1,2,4,5-tetrazine-3,6-dicarboxylic acid are reported. These compounds were prepared by a two-stage synthesis: re-esterification of dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate in the presence of aluminium triethoxide and subsequent dehydrogenation of dialkyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylates. The structures of the prepared compounds were confirmed by NMR and mass spectra.