AbstractHydrolysis resistance and mechanism of reaction products of hydroxymethylated 2‐substituted (X) 4,6‐diamino‐s‐triazines (MXT) with cotton fabrics has been studied. Finishing reagents used were MXT having the following substituents: X = CH3O (MMT), (CH3)2CHO (MIPT), CH3 (MAG), C2H5NH (MEM), HOC2H4NH (MHEM), and (HOC2H4)2N (MBHEM). For comparison, trimethylolmelamine (TMM), dimethylolurea (DMU), dimethylolethyleneurea (DMEU), and dimethylol‐ethyltriazone (DMET) were used. Hydrolysis was carried out in buffer and NaOH solutions of various pH's for 30 min at 80°C. The order of hydrolysis resistance of crosslinked reagents was determined from the nitrogen contents retained. It was as follows: pH 1, MROT < MRNT < MRT; pH ≧ 2, MROT > MRT > MRNT; pH ≦ 13, MROT > MRNT; pH 14, MROT < MRT < MRNT, where MROT is hydroxymethylated 2‐alkoxy (MMT, MIPT), MRT is hydroxymethylated 2‐alkyl (MAG), and MRNT is hydroxymethylated 2‐alkylamino‐4,6‐diamino‐s‐triazine (MEM, MHEM, MBHEM). This fact can be explained in terms of the basicity constant (pKb) of crosslinked MXT with cotton (approximately pKb) of 2‐substituted 4,6‐diamino‐s‐triazine (XT). The hydrolysis rates of crosslinked MMT, MAG, and MEM were determined at pH 2. The activation energies were 21.8 for MMT, 20.9 for MAG, and 21.0 kcal/mole for MEM.