Hydrocarbon (HC) compounds move in the subsurface with or without water. Petrochemical plants and airports may have subsurface pollution plumes caused by spilled hydrocarbons. To locate and determine the size, extent and movement of HC in the underground, were the purpose of investigations near the towns of Saratov in Russia and Witbank and Louis Trichardt in South Africa. Our search for HC compounds in the subsurface was based on the presence of an induced polarization (IP) effect of the electro-osmosis type, superimposed on time domain electromagnetic (TDEM) soundings response stemming from groundwater contaminated by HC. In the sounding results obtained, IP effects distort the TDEM signals. Follow-up drilling results confirmed that the contaminant plume could be mapped by identifying the IP effects on the individual soundings. However not all soundings that predicted the presence of HC were correct (only about 70%) and further studies are undertaken to isolate the cause of IP effects that mimic the HC polarization effect.