Bioremediation has achieved acceptance as a cost-effective technique for the remediation of soils and groundwater contaminated with petroleum hydrocarbons (PHC). A range of laboratory techniques to assess the biodegradability and bioavailability of PHCs are presented. Biodegradability and bioavailability are important determinants of the bioremediation performance of PHCs. Novel methods for the assessment of the bioavailability of PHC components are described. The techniques are demonstrated for a hydraulic fluid and a spindle oil from a contaminated site. Biodegradation is measured by oxygen consumption and carbon dioxide production. Bioavailability of the PHCs is estimated based on the PHC-water partitioning of tracer compounds and a novel analysis of gas chromatograms based on Raoult's law. The PHCs tested were only partially biodegradable (< 25% in 78 d) due to the low solubility and likely recalcitrance of some of their components. The combination of techniques outlined is expected to be of use in assessing the likely bioremediation performance of PHCs for which published data are scarce or inadequate.