This paper presents field experiences obtained with a new technology for detecting petroleum pollution in soil and ground water based on “in situ” determination of hydrocarbon concentrations in soil air. Ecoprobe is a new soil gas device from RS-Dynamics in the Czech Republic. The rugged waterproof device is equipped with a built-in computer controlled semiconductor sensor. Three case histories are presented that demonstrate the use of the equipment under typical conditions. Two case histories present the use of the device under typical field conditions; the third case history compares results from the Ecoprobe and a commercial photoionization detector (PID) device.