A novel resin NKZ, which is a macroporous resin intermediate modified with nitroguanidine, was synthesized and identified. The adsorption behavior of five kinds of water-soluble dyes onto the resin NKZ was investigated thermodynamically in detail. The results showed that the adsorption rate for reactive brilliant blue KN-R is higher than those for the other dyes. The equilibrium data can be well-described by a three-parameter equation. The values of DeltaGdegrees demonstrate that the first layer adsorption of the dyes onto NKZ involves both physical adsorption and chemisorption but multilayer adsorption is a physical one. Both the values of DeltaHdegrees and DeltaSdegrees on the adsorption of reactive brilliant blue KN-R onto NKZ was positive, indicating that the adsorption is endothermic and can occur spontaneously. The apparent activated energy (E-a) of the adsorption process was 16.84 kJ/mol, which shows that there is a great potential barrier for adsorption.