Poly(hydrazino-1, 3, 5-triazines) were prepared by the meltpolymerization of 2, 4-dihydrazino-6- substituted (R')-1, 3, 5-triazines (R' =amino, dimethylamino, diethylamino, dipropylamino, dibuthylamino, methyl, phenyl) with 2, 4-diphenoxy-6-(N, N-disubstituted)amino (R2N-)-1, 3, 5-triazine(R= hydrogen, methyl, ethyl, propyl, buthyl). The intrinsic viscosities of the poly-hydrazino-1, 3, 5- triazines in formic acid at 30° C, ranged from 0.07-0.73 dug, except for the polymer which have the amino, group in 1, 3, 5-triazine ring. The intrinsic viscosities of the latter ranged from 0.01-0.06 dg. The lower value was considered to be due to 2-amino-4, 6-dihydrazino-or-diphenoxytriazine unit which contains three functional groups. The poly(hydrazino-1, 3, 5-triazines) were soluble in formic acid, acetic acid, sulfulic acid, nitric acid, hydrochloric acid, and ethylene chlorhydrin, but were insoluble in m-cresol and dipolar aprotic solvents. Polymers which have the amino or methyl group in 1, 3, 5-triazine ring showed poor solubility. The thermal stability of the polymers were measured in nitrogen by thermogravimetrie analysis and differential thermal analysis, and were found to decompose at 310-s340° C. IR spectra of model compounds i. e.2- (N, N-dimethylamino)-4, 6- (3, 5-bis(N, N-diethylamino)-2, 4, 6-triazinyl hydrazino) -1, 3, 5-triazine mp 1O2-4O2-° C, and 2-(N, N-dimethylamino)-4, 6-3, 5-bis(N, N-dimethylamino)-2, 4, 6-tria. zinyl hydrazino -1, 3, 5-triazine mp 142-144° C, were compared with those of the corresponding polymers. Their chemical structures were determined by NMR spectra.