A fundamental fixed-bed catalytic reactor model has been developed for use in selecting alternative operating strategies,on a commercial methyl-t-butyl ether (MTBE) unit. The model is based on general chemical engineering principles and is tuned to represent the operation of the reactor’s system of a given MTBE unit. Constrained optimization techniques are used to determine the optimum operating conditions of the reactor’s system that give the maximum net profit. The model will enable the user to predict the required bed temperature rises, the required recycle rate for specific single-pass conversion and the required heat removal rate in the coolers of an existing unit. For optimization purposes, the model is used to investigate the effect on unit profitability when variables such as the conversion per pass or the total conversion were modified. A computer program, MTBEC, was developed for solving the model equations. Conversion per pass was varied from 62.3% to 87.3% in increments of 5%. Based on these cases, conversion per pass higher than the original design value of 72.3% is suggested. The optimum conversion per pass value appears to be about 75.5% and represents an improvement of about 1.5% on daily net profit for the prices quoted. These results demonstrate the use of the model in selecting more economically attractive operating targets. The model can also be used to investigate the effect of other variables amenable to optimization, e.g. fresh feed stock quality, feed costs and bed temperature profiles.