A method for leakage measurement of a test object filled or fillable with a test fluid, comprising the following steps: - arranging the test object in a closed test chamber filled with a reference fluid in order to enrich any test fluid leaking into the reference fluid of the test chamber; - operating (S3, S6) a fluid sensor (91, 91') sensitive to at least one constituent of the test fluid to excite it by energizing it by heating to an excitation temperature, by applying an electric field, by optical excitation or by electrochemical pumping so that an amount of chemical reactants exceeding a thermodynamic equilibrium is formed on a sensor surface of the fluid sensor (91, 91'), wherein after excitation the fluid sensor (91, 91') is brought into a measurement state in which a thermodynamic inequilibrium exists with respect to chemical reaction partners on the sensor surface of the fluid sensor (91, 91') at least during a measurement period, wherein the amount of chemical reactants exceeding the thermodynamic equilibrium influences an electrical property of the fluid sensor (91, 91'); - after excitation of the fluid sensor (91, 91'), applying the sensor surface with at least a part of the reference fluid possibly contaminated with test fluid for the measurement period, so that the thermodynamic inequilibrium is reduced by applying with corresponding constituents of the test fluid and a change in an electrical property results due to an interaction of the test fluid with the reactants, - determining (S8, S9) a leakage indication as a function of the change in the electrical property of the fluid sensor (91, 91') due to the application of the contaminated reference fluid on the sensor surface during the measurement period. - arranging the test object in a closed test chamber filled with a reference fluid in order to enrich any test fluid leaking into the reference fluid of the test chamber; - operating (S3, S6) a fluid sensor (91, 91') sensitive to at least one constituent of the test fluid to excite it by energizing it by heating to an excitation temperature, by applying an electric field, by optical excitation or by electrochemical pumping so that an amount of chemical reactants exceeding a thermodynamic equilibrium is formed on a sensor surface of the fluid sensor (91, 91'), wherein after excitation the fluid sensor (91, 91') is brought into a measurement state in which a thermodynamic inequilibrium exists with respect to chemical reaction partners on the sensor surface of the fluid sensor (91, 91') at least during a measurement period, wherein the amount of chemical reactants exceeding the thermodynamic equilibrium influences an electrical property of the fluid sensor (91, 91'); - after excitation of the fluid sensor (91, 91'), applying the sensor surface with at least a part of the reference fluid possibly contaminated with test fluid for the measurement period, so that the thermodynamic inequilibrium is reduced by applying with corresponding constituents of the test fluid and a change in an electrical property results due to an interaction of the test fluid with the reactants, - determining (S8, S9) a leakage indication as a function of the change in the electrical property of the fluid sensor (91, 91') due to the application of the contaminated reference fluid on the sensor surface during the measurement period.