Non-exhaustive extraction techniques (NEETs) have been shown to measure the putatively bioavailable fraction of hydrophobic compounds in soil. To date, these studies have only considered bioavailability in a single soil type. In this study, naphthalene was amended into five different soil types and mineralisation, bacterial biosensor response and the number of indigenous microbial naphthalene degraders were determined. Two NEETs were used to extract the naphthalene from soil; hydroxypropyl-cyclodextrin (HPCD) and XAD-4. The HPCD extractable fraction correlated closely (R-2 = 0.917) with the portion that was mineralised, but the XAD-4 extract did not (R-2 = 0.044). HPCD may be ideal for the rapid assessment of the fraction of a hydrophobic organic contaminant that is available for biodegradation. A NEET that complements environmental microbial analysis will enhance our understanding of soil pollution interactions and equip us better in designing risk assessment models that integrate biological parameters. This application, although refined for soil samples, should be transferable to other environmental matrices. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.