Bioventing is an improved method of soil remediation that is being used with increasing frequency. In this paper, we refine techniques to measure the progress of petroleum hydrocarbon decomposition by monitoring vapor phase composition with synchronous scan fluorescence spectroscopy (SSFS). Analysis of the vapor phase has advantages compared to standard extraction techniques that require extensive sample handling and clean up. For comparison, hydrocarbon contamination in the soil was measured by analysis of Soxhlet extractions with gas chromatography-mass spectrometry (GC-MS). Comparison of the GC-MS and SSFS data showed that changes in hydrocarbon composition measured in the vapor phase provide an accurate measure of decomposition reactions taking place in the soil.