Failure to thaw frozen mcat adequately is considered to be a contributory factor in sporadic outbreaks. Although much of the frozen products are thawed domestically. there are circumstances where frozen foods may be thawed for additional processing. Because the thawing process is generally assumed to be identical to that of freezing, any solution applied to freezing should also be valid for thawing. However, care must be taken when using these solutions, because the mass transfer at the product-air interface is of great importance in thawing. In this study heat and mass transfer during the thawing of ham as analysed. A computer program using the explicit finite difference scheme was implemented. The developed procedure was used to examine the influence on the thawing time of carious operating conditions and physical properties. The results showed that the effect of the uncertainty of thermophysical properties on the prediction thawing time is important. The results of the simulation were compared with experimental measurements, and the predictive values were found to agree comparatively well with the experimental ones. (C) 2003 Elsevier Science Ltd. All rights reserved.