This study presents an upgrading of the mathematical models to predict anaerobic biogasification potential (ABP) through quick laboratory analyses that have been presented in an earlier study. The aim is to widen the applicability of the models to heterogeneous organic substrates and to improve their reliability through a deeper statistical approach. Three multiple-step linear regressions were obtained using biomass oxygen demand in 20 h (OD(20)) plus the volatile solids content (VS) of 23 new samples of heterogeneous organic matrices, of 46 samples presented in the earlier work and of the data set comprising all the 69 samples. The two variables chosen were found to be suitable for very heterogeneous materials. To judge the prediction quality, a validation procedure was performed with 12 new samples using model efficiency indexes. The proposed model had good prediction ability for a large variety of organic substrates, and allows the calculation of the ABP value within only 2-day's laboratory work instead of the 60-90 days required to obtain ABP by anaerobic test. (C) 2009 Elsevier Ltd. All rights reserved.