[en] The X-ray spectrum of Cas A was observed for several days by the GSFC proportional counter experiment on board OSO-8. The high-energy (>5 keV) data are well fitted by a thermal spectrum with kT=3.9 (+0.9,-0.4) keV. A narrow iron line which is predicted by the thermal model is also observed, centered at 6.66 (+0.14,-0.16) keV with an equivalent width of 1270 (+175,-40) eV. The low-energy (2--5 keV) data show an excess over the high-temperature component which is consistent with the presence of an additional low-temperature thermal component with kTapproximately-less-than0.7 keV and N/subH/approx. =10²² atoms cm^-2. Iron abundance in the source relative to normal cosmic abundance is discussed, as in the relation of this observation to shock wave and multicomponent thermal models for supernova remnants