This study is focused on the investigation of the effect of thermal shock cycling on the mechanical properties of cellulose based reinforced polymer composites. Polymer composites reinforced with olive pits powder at different filler-volume fractions were manufactured. An increase in the bending modulus on the order of 48% was achieved. On the other hand, results showed that the bending strength remained almost unaffected from the amount of filler introduced. Next, the effect of thermal shock cycling on the mechanical behaviour of the thus manufactured composites was investigated. Theoretical predictions for both the properties variation with number of thermal shock cycles applied as well as with filler-volume fraction were derived using the residual properties model (RPM) and the modulus predictive model (MPM), respectively. Predicted values were compared with respective experimental results. In all cases, a fair agreement between experimental findings and theoretical predictions was found. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 67-76,2012