Adsorption of ferric oxinate in some surfactant solutions on textile fibers revealed a maximum and a minimum value in previous paper. The authors supposed that adsorption of surfactant on the fabrics may play an important roll to interprete this phenomenon. Under this consideration, adsorption equilibriums of four non-ionic surfactants of polyoxyethylene-nonyl-phenol ether type (n=8, 9, 11, and 15) at different temperatures (30°, 40°, and 50°C) on cellulosic fiber have been studied. The results were plotted by Langmuir and Freundlich's adsorption isotherms and thermodynamic parameters ( Δ μ°, ΔH °, ΔS °) were calculated to interprete the phenomena in comparison with those about wool. 1) N. Watanabe & A. Yabe : Kaseigaku Zassi, 22, 263 (1971). 2) Y. Nemoto et al . : J. Chem. Soc. Japan (Ind. Chem. Edition), 68, 2173 (1965).