Studies on the radical, thermal decomposition of 11 starch varieties revealed that among amaranthus, cassava, oat, maize, waxy maize, rye, triticale, two varieties of potato and two varieties of wheat starch the oat starch was least stable and waxy maize starch was the most stable. The stability determination was based on the free radical count in the EPR spectra. The radicals appeared to be very stable against air as well as water and alcohol used for extraction of dextrins resulting from the thermolysis of starch. Simulations of the EPR spectra for 12 glucosyl radicals and the comparison of experimental and simulated spectra led to the conclusion that the delocalization of unpaired spin as well as steric hindrances are responsible for that stability. In order to prepare novel dextrins of increased water binding capacity accompanied by low aqueous solubility thermolysis of starch was carried out under nitrogen, carbon dioxide, ammonia and hydrogen sulfide. The conventional and microwave heating of plain starch and its blends with formaldehyde, carboxyamides and esters were tested. The results are compared and discussed.