A new approach to the preparation of standard gaseous mixtures based on thermal decomposition of surface compounds, has been reviewed. The method is used to prepare standard mixtures containing volatile analytes such as thiols, isothiocyanates, carbon monoxide, carbon dioxide, ammonia, amines, ethylene and methyl chloride. The method enables the preparation of the standard immediately before a calibration step. It is specially useful for the generation of standard mixtures containing volatile, malodorous, unstable and toxic compounds.