The mobility of cyclohexane in a microporous silica powder has been studied by neutron scattering and NMR techniques at different temperatures and loadings. The silica powder has the same characteristics as the corresponding supported membrane. Self-diffusion coefficients of the order of 10(-10) m(2) s(-1) are obtained by both techniques at 300 K, the activation energy being ca. 11 kJ mol(-1). The same value was also found for benzene diffusing in the same silica sample, this implies that there are no specific interactions with silica. The dimension of the pores between the voids of the non-porous silica particles is of the order of 1 nm.