The equilibrium sorption of Orange II by silk fibroin in the range of 50$^{circ}$, 70$^{circ}$, 90$^{circ}C$ and to pH 1.5, 2.2, and 4.0 have been discussed in the light of the dual sorption. Langmuir sorption constant K$\_$L/ and partition coefficient K$\_$P/ were decreased with the increase of the temperature and the pH for the dyeing of silk fibroin with Orange II. Positive values for adsorption entropy were observed. It was found that the values of $Delta$H$^{circ}$ is negative for dyeing conditions, and the dyestuff/fibre reaction is therefore exothermic.refore exothermic.