The kinetics of nucleation and crystal growth in drowning-out crystallization using a T-mixer were estimated using crystal size distribution, taking into account a size-independent growth. At the conditions of the feed compositions investigated, the product weight mean size changed from 7-29 mu m when the residence time varied between 0.32 and 0.61 s. Nucleation and growth rates were expressed simply as a function of the residence time. The T-mixer can be used to generate high levels of supersaturation due to inducing micro-mixing effects. The particle size correlated well with the ratio of growth rate to nucleation rate. Finally, the particle size obtained in drowning-out crystallization using a T-mixer was found to be proportional to the 1.69th power function of the residence time.