The use of reference materials in analytical laboratories is on the increase. Undoubtedly, the reason for this is the need for traceable and therefore comparable results of measurements. The use of reference materials is necessary in all analytical laboratories and especially in those which examine environmental samples characterised by:- low or very low concentration levels of analytes,- complex matrices- temporal and spatial variability of samples, and- the possibility of interference.The development of analytical techniques for measuring components of gaseous media (outdoor air, indoor air, workplace air) has been going on for many years. This trend is closely associated with the need to obtain results of high quality, which necessitates the use of matrix-free (standard gaseous mixtures) as well as matrix reference materials. The use of reference materials with matrix compositions and analyte concentrations close to those of real samples yields more reliable measurement results.This article presents a new approach to the problem of generating standard gaseous mixtures: the analyte is generated during the thermal decomposition of compounds immobilised on (i.e. chemically bonded to) the surface of an appropriate support material.