A kind of novel surface-active dye containing fluorocarbon groups was investigated. The diffusion coefficients at different temperature and the activation energy of the dye in silk fabric were discussed, respectively. The diffusion coefficient increased as temperature rising. The results show that values of diffusion coefficients D of the novel surface-active dye are higher than those of Reactive Blue X-BR. The apparent activation energy of Novel Dye 3 was lower than that of Reactive Blue X-BR. The novel surface-active dyes containing fluorocarbon groups showed good diffusion property in silk fiber. (c) 2007 Elsevier B.V. All rights reserved.