Natural oilsands deposits are composed of a complex mixture of sand, silt, clay, water and bitumen. The bitumen content and silt fraction, or fines (< 44 mum), have traditionally been used as primary measures of ore processability. However, it is now known that this rule of thumb is not always applicable. In fact, the variability of oilsands, in terms of both quality and composition, makes it difficult to determine the unbiased effect of any individual component on bitumen extraction from mined ore. To address this problem, a model oilsands (MOS) system has been devised to determine how the interactions of oilsands components affect bitumen recovery. In this preliminary work, the effects of bitumen and fines contents, connate water pH and sodium hydroxide (NaOH) dosages on primary bitumen recovery were determined under the conditions extant in the warm slurry extraction process (WSEP). A three-factor Box-Behnken experimental design was used to quantify the effects. Prior to incorporation into the model oilsands system, each component was characterized to ensure quality control between tests. For the simple model studied in this work, the fines content and sodium hydroxide addition were the most important parameters affecting primary bitumen recovery. Although a small amount of fines was required to recover bitumen in the absence of process aids, an excess of fines was always detrimental to bitumen recovery. Crown Copyright (C) 2002 Published by Elsevier Science Ltd. All rights reserved.