The present study is conducted to compare the performance of different oxidation processes such as the solar photo-Fenton, the solar photocatalyst of TiO2 and solar photocatalyst of TiO2/Fenton process for the treatment of petroleum wastewater from Sohar oil refinery (SOR) by a central composite design (CCD) with response surface methodology (RSM). The degradation efficiency is evaluated in terms of chemical oxygen demand (COD) and total organic carbon (TOC) reductions. The solar photocatalyst of TiO2/Fenton method improved the performance of photocatalyst TiO2 in the normal value of pH (7) for petroleum wastewater, therefore no need to adjust pH during this treatment. In acidic conditions pH <7, the solar photo-Fenton process is more efficient than the solar photocatalyst of TiO2 process, while it is less efficient than the solar photocatalyst of TiO2 process in alkaline conditions pH >7. The TiO2 dosage and pH are the two main factors that improved the TOC and COD removal in the solar photocatalyst of TiO2/Fenton and the solar photocatalyst of TiO2 processes while the pH and H2O2 concentration are the two main factors in the solar photo-Fenton process.