An experiment for the particle growth in gelatin was performed. Particle is a solid solution of (Ba,Sr)SO4. First of all, we performed a counter-diffusion type experiment where BaCl2 and SrCl2 diffuse in gelatin and Na2SO4 diffuses toward the opposite direction. This is a condition proposed by Putnis et al. (1992). Oscillatory zoning found out by Putnis et al. (1992) was reproduced. Then, chemical composition changed periodically in a particle, thickness of each circular stripe being several microns in the order of magnitude. In order to investigate the particle growth process in a gel, we performed experiments for particle growth with several kinds of processes with reactions and diffusions. In these experiments, some kinds of chemical species were dissolved in gelatin, and other chemical species were diffused in gelatin. Findings of this work indicated that core portions of particles of the reaction-diffusion process were mainly composed of BaSO4 which determines fundamental shape of particles. After formation of this core, hemicylindrical portions with Sr-rich composition were deposited on the surface of the core. Although the characteristics were always kept for all of the experimental conditions of this work, the rate of deposition of hemi-cylindrical portion was dependent on the way of diffusion which was controlled by an experimental setup and gelation time. Fundamental information for particle growth in gel was obtained in this work, and potential activity for particle formation with reaction-diffusion mechanism was pointed out.