The adsorption of the nonionic surfactant hexaethylene monododecyl ether, C12E6, and the mixed nonionic/cationic surfactants C12E6 and hexadecyl trimethyl ammonium bromide, C(16)TAB, onto the hydrophilic and hydrophobic surfaces of thin cellulose films, formed by Langmuir-Blodgett. L-B, deposition, have been studied by neutron reflectivity. For the surfactant mixtures, considerable nonideal mixing is observed at both hydrophobic and hydrophilic surfaces. The results demonstrate that the C12E6, C12E6/C(16)TAB mixture and solvent have a greater penetration into the cellulose film upon adsorption, compared to that observed in previous studies of C(16)TAB adsorbed onto cellulose, due to the presence of the nonionic surfactant. From the range of measurements made, it is concluded that both the presence of the nonionic surfactant and the nature of the cellulose films are both contributing factors to this increased penetration and swelling of the cellulose film.