In this study, an aqueous-based hydroxypropyl-beta-cyclodextrin (HPCD) extraction technique was assessed for its capacity to determine the microbially degradable fraction of mono- and polycyclic aromatic hydrocarbons in four dissimilar soils. A linear relationship (slope = 0.90; R-2 = 0.89), approaching 1:1 between predicted and observed phenanthrene mineralization, was demonstrated for the cyclodextrin extraction; however, the water only extraction underestimated the microbially available fraction by a factor of three (slope = 3.35; R-2 = 0.64). With respect to determining the mineralizable fraction of p-cresol in soils, the cyclodextrin extraction (slope = 0.94; R-2 = 0.84) was more appropriate than the water extraction (slope = 1.50; R-2 = 0.36). Collectively, these results suggested that the cyclodextrin extraction technique was suitable for the prediction of the mineralizable fraction of representative PAHs and phenols present in dissimilar soils following increasing soil-contaminant contact times. The assessment of the microbial availability of contaminants in soils is important for a more representative evaluation of soil contamination. (c) 2006 Elsevier Ltd. All rights reserved.