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In this research paper a study of the thermal processing progress in food using microwaves was carried out. In particular, cylindrical and cubical potato samples, 5% w/w and 10% w/w starch suspensions in quantities of 80 g and 240 g and cylindrical 20% w/w starch gels were prepared. Potato samples were processed at three different power conditions (Low, Medium, High) and factors such as % loss of moisture and the % heat processed area as measured with the ImageJ program were studied. Starch suspensions were processed at three different power conditions (Low, Medium, High) and factors such as the final temperature (°C) and the changes of the mean diameter (D (4,3)) of the starch granules were studied. Starch gels were processed at two different power conditions (Low, Medium) and factors such as % loss of moisture and changes of the Young modulus of elasticity as measured by the Texture Analyzer were studied. The morphology of the heat processed area and size of the starch granules in the starch suspensions were also studied by optical microscopy. Results showed that the power, the processing time and the geometric shape of the samples affected the % loss of moisture and the % heat processed area in potato samples. It was also found that the power, the processing time and the quantity of the sample affected the final temperature and the mean diameter of the starch granules. This increase did not occur in the starch suspensions with different concentrations. Results for starch gels showed that the power, the processing time and the number of samples in the oven affected the % loss of moisture and changes of Young modulus of elasticity. The results of this study could be used as guidelines or indications for the industrial production and processing of food using microwaves