The solvent free esterification reaction between stearic acid and stearyl alcohol has been examined with a montmorillonite clay as catalyst. To aim for industrial application the system has been studied on reaction rate, product purity, catalyst behavior and water removal as function of the process conditions. To avoid an etherification side reaction and to aim for the highest reaction rate, the temperature should be strictly maintained at 170 degrees C. This is provided on larger scale by the application of microwave heating. Although the examined Bronsted acid clay was found to lose its catalytic activity at very low water activities, a yield of 95 % pure stearyl stearate can be obtained by simply filtering of the clay without solvent extraction or distillation. The "waxy" esterification reaction was investigated with the pilot plant continuous microwave dry-media reactor (CMDR). The reaction time needed for 95 % yield was reduced by a factor 20-30 in comparison with industrial conventional reactors. This was due to the more homogeneous heat transfer of microwaves, which allows to reach a higher bulk temperature.