This paper presents a model that allows to describe the absorption of hydrogen isotopes by a thin sample with known geometric dimensions. The sample was saturated with hydrogen isotopes from the gas phase at a given temperature in experimental chamber under uncompensated pressure. The initial pressure and gas composition of hydrogen isotopes mixture was fixed. The model was applied to describe the results of experiments on the saturation of V4Cr4Ti vanadium alloy sample with hydrogen isotopes. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.