Melamine formaldehyde oligomers with peroxy groups (MFOP) have been synthesized based on melamine or urea and melamine in the presence of tert-butyl peroxymethanol or tert-butyl hydroperoxide. Zinc oxide was used as a catalyst. The effect of peroxide nature, ratio of the starting components and process time on the characteristics and yield of MFOP has been studied. The structure of the synthesized MFOP was confirmed by IR- and PMR-spectroscopy. The chemistry of the cross-linked structures formation was studied. The possibility of using such oligomers as a cross-linking agent for the mixtures based on TGM-3 oligoesteracrylate is shown.