Electronic speckle pattern interferometry has been applied for studies of diffusion fields near a single crystal of potassium dihydrogen phosphate (KDP), growing in tetramethoxysilane (TMS) gel. The experimental procedure together with the advantages of speckle interferometry allowed us to study the development of diffusion field after a sudden switch of supersaturation. Comparing experimental data with the results of numerical simulation we have evaluated the linear kinetics coefficient B during gel growth. The obtained value was about three times smaller than that in gel free solution what suggests interaction of crystal surface with the gel net. (C) 2002 Elsevier Science B.V. All rights reserved.