Contamination of groundwater by methyl tertiary butyl ether (MTBE), that is detected in wastewater of petrochemical industry, is an increasing problem to water supply companies. The subjects of this research were the methods of photolytic, photocatalytic and microbiological degradation of methyl tertiary butyl ether (MTBE) dissolved in wastewaters. The effects of concentrated solar radiation simulated with sodium lamp (SONT UV 400) have been investigated in laboratory experiments. Our result indicated that bacteria Pseudomonas strain CY, isolated from the kerosene, and added alone, was able to gradually degrade MTBE and to decrease its concentration for 93.6% in 12 h. However, the percentage of photolytic degradation decrease in only 4 h was 99.2%. By adding Pseudomonas strain CY after 4 h of light treatment, the degradation was enhanced to 99.55% in additional 5 h. The photocatalytic process was performed in slurry-catalyst reactor with different concentrations of TiO2 catalyst: 5, 0.5 and 0.25 g/L. The MTBE degradation producing carbon dioxide reached 91% in only 150 min, when 5 g/L of catalyst was used.