This contribution investigates the crystallization behavior of amorphous silicon films on glass by using pulsed lasers with very high repetition rates up to 100 kHz. We determine the influence of the laser repetition rate f and of the film thickness d on the grain width g of the resulting polycrystalline silicon films. Our experimental results indicate a strong dependence of the grain width g on film thickness d as well as on the repetition rate f of the laser. The grain width rises from g = 0.27 µm to g = 3.59 µm if the film thickness increases from d = 50 nm to d= 300 nm and the repetition rate f from f = 20 kHz to 100 kHz. We use a purpose developed two- dimensional finite difference numerical model to calculate the evolution of the temperature in the silicon film and in the glass substrate. An increase of both, the film thickness d, and the repetition rate f decrease the solidification velocity v of the film. A comparison of the solidification velocity vs and the measured grain width g shows a linear correlation.