A photoemission study of Si-rich polar and nonpolar 4H-SiC surfaces before and after initial oxidation are presented. Core level and valence band data recorded using synchrotron radiation are utilized to explore the properties of these surfaces and of the interfaces. The Si-rich surfaces showed three prominent surface Si 2p components. These components are strongly attenuated upon oxygen exposures and can not be detected after an exposure of 3000 L. After exposures of ≥ 200 L the number of oxidation states, i.e. Si+1, Si+2 and Si+4 oxidation states, and also their shifts are found to be the same as after initial oxidation of the same surfaces prepared by in situ heating. Only one sharp C 1s core level is observed on the Si-rich surfaces. This is quite different compared to earlier findings on the same surfaces prepared by in situ heating where prominent surface shifted C 1s components are found. After oxygen exposure of ∼ 200 L the C 1s peak is broadened and an asymmetry is observed on the high binding energy side. This together with the Si 2p results show that oxygen exposures of ∼ 200 L affect not only the Si overlayers. Layers in the SiC substrate are also affected since the C 1s peak is broadened and the Si 2p spectrum show the same oxidation states as after large exposures and after oxidation of these surfaces prepared without Si overlayers.