  Measurements of the Sunyaev-Zeldovich (hereafter SZ) distorsion of the cosmic
microwave background can give interesting physical informations on clusters of
galaxies, provided that the electronic temperature of the gas is known.
Previous attempts to do so have used the electronic temperature determination
obtained from the X-ray spectra. However, if the intergalactic gas is not
homogeneous, the X-ray emission will trace the denser component, and the
temperature determination may not be relevant for the lower density gas which
is dominating the SZ measurements. Moreover, the X-ray brightness decreases
very rapidly with the distance, which is not the case for the SZ effect.
Distant clusters might be detected from SZ measurements, whereas they are
inaccessible to X-ray observations. For these reasons, we have investigated the
possibility to derive the electronic temperature of the gas from the SZ
measurements in the submillimeter range (lambda ~ 300-600 micro-m). We show
that given the sensitivities of the future submillimeter space missions Planck
Surveyor and FIRST, the electronic temperature of massive clusters
(Y_center=3*10^{-4}) can be determined with an accuracy ranging from 1 to 4 keV
depending on its distance and the data avalaible.
