We have investigated the kinetics of grain growth phenomenon in heavily phosphorus doped polycrystalline silicon for different doping concentrations, annealing times and temperatures, using a model based on the thermodynamical concepts. Explicit expressions for the grain growth rate and the size for normal grain growth have been derived and numerical evaluations have been made using the computer simulation technique. The simulated values have been compared with the experimental observations. The kinetic model has been extended to determine the grain size distribution in polysilicon. The grain size distribution has been presented for various values of phosphorus concentration and different values of time and temperature of annealing. The results are discussed in detail. © 1990.