NOVELTY - The method involves arranging a gas adsorbent medium (5) within a vessel. Total amount of gas (15) stored in an sorption store (1) is computed based on a measured temperature value and a measured pressure value and based on an empirical model defining relation between the total amount of gas stored in the sorption store, where parameters of the empirical model are fitted to experimental data. Amount of gas present in a gas phase is computed in first step. Amount of gas adsorbed by the gas adsorbent medium is computed in second step.    USE - Method for indicating fill level e.g. amount of gas, stored in a sorption store e.g. adsorbed natural gas (ANG) tanks, to a driver of a vehicle (all claimed) e.g. lorry and car, during drive or charge process at a filling station in mobile storage applications. Uses include but are not limited to natural gas, methane, ethane, butane, hydrogen, propane, propene and ethylene.    ADVANTAGE - The method enables measuring current temperature and current pressure in or at the vessel of the sorption store so as to indicate fill level of the sorption store to a driver of a vehicle during drive or charge process at a filling station. The method enables predicting increase of temperature during filling process and determining maximum dosage so as to prevent overheating of a surfacewall of the vessel. The method enables shifting a temperature sensor to a side of an inlet to avoid interfered filling process.    DETAILED DESCRIPTION - The gas adsorbent medium is a porous and/or microporous solid. The vessel is a pressure vessel. The gas is selected from a group comprising of natural gas, methane, ethane, butane, hydrogen, propane, propene and ethylene. INDEPENDENT CLAIMS are also included for the following:    (1) a sorption store    (2) a vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a side view of a vehicle comprising a control unit.    Sorption store (1)    Gas adsorbent medium (5)    Temperature sensor (11)    Temperature sensor (13)    Gas (15)