Two possible ways of crystallite downsizing of cocarboxylase hydrochloride namely mechanical milling and precipitation under high supersaturation conditions were studied as well as their influence on the drying parameters of the produced powders. It was found that both methods allowed shortening drying times of powders. However, precipitation from highly supersaturated solutions was found to have a more significant effect on cocarboxylase hydrochloride drying in comparison with the milling as the crystallites produced by the former method have smaller sizes (<10 mu m) without additional disintegration and contain much less inclusions of mother liquor. Obtaining solutions with high supersaturation degrees was achieved due to application of microwave irradiation at the evaporation stage that provided uniform gradientless heating of cocarboxylase aqueous solutions. The results of this work can be applied for producing other fine-crystalline substances and materials when particle sizes play a key role in the manufacture of products with the desired qualitative characteristics. (C) 2010 Elsevier B.V. All rights reserved.