Thin laminar CdTe nanoflake membranes grafted by oleic acid were investigated for sorption characteristics and permeation of permanent gases and hydrocarbons depending on the process temperature. A huge influence of temperature was revealed, enabling enhancement of the ideal selectivity for butane-methane separation from 28 to over 100 with the change of process conditions from 25 °C to 10 °C. The separation factor attains 26 in mixed-gas CH4/C4H10 separation experiments. Both sorption enthalpy and activation energy of diffusion were evaluated for penetrants, exhibiting the role of low activation barriers in fast transport of condensable hydrocarbons. The experimental results were proved by a semi-empirical calculation, illustrating swelling of grafted layer with heavy hydrocarbons. The effect was proved experimentally with in situ diffraction experiment. The low activation energy for the transport of condensable hydrocarbons, strong temperature dependence of permeance, and huge extinction coefficient of CdTe nanoflakes enable modulating the membrane permeance with laser irradiation, demonstrated with permeance photoswitching. Display omitted •Sorption enthalpy and activation energy of diffusion were evaluated for penetrants.•Fast transport of heavy hydrocarbons governed by low activation barriers of diffusion.•Low activation energy of heavy hydrocarbons governed by swelling of the grafted layer.•Swelling of the grafted layer with heavy hydrocarbons was proved by in situ X-ray diffraction.•The permeance photoswitching was demonstrated under laser irradiation.