The oxide growth of porous 4H-SiC and its dependence on time of oxidation have been measured. Both Si-face and C-face SiC substrate were oxidized in wet oxygen at 1000degreesC. Oxide steps were produced by a photolithographic process followed by HF-etching. The oxidation rate of the porous layer on both faces of the substrate was less than the plain C-face but higher than the plain Si-face.