The kinetic behavior of both crystallization and dissolution of solid particles in liquid solutions is investigated. The effect of heat on the phenomena under consideration is taken into account. Although the present analysis is based on ellipsoidal particles, it can be extended to particles of various geometries by choosing an appropriate transformation. We show that the rate of dissolution increases with the decrease in particle size, and the greater the curvature of a surface, the faster the rate. On the other hand, the rate of growth of a crystal decreases with the increase of its size. For both dissolution and crystallization, the greater the curvature of a surface, the faster the rate of change in the particle size. In the analysis of the effect of the heat of dissolution/crystallization, we conclude that the rate of variation in the size of a particle for dissolution follows the order exothermic>isothermal>endothermic. No general rule is found for crystallization. The experimental data for the growth of ferrite allotriomorphs in Fe-C alloys reported in the literature is analyzed to justify the applicability of the present model.