A semi phenomenological and global chemical kinetic model is adopted and applied to predict soot formation in gasoline-fueled spark ignition engines. The adopted model considers acetylene produced from gasoline pyrolysis process as the main precursor for soot inception. The adopted soot model was initially proposed for diffusion flames and this work tries to apply and modify it to gasoline fueled (premixed flame) spark ignition engines. The burned mass fraction and burn rate are used to estimate the instantaneous acetylene, oxygen and Hydroxyl (OH) radical mass fractions at each crank angle of the engine. Experimental data from a single point throttle body injected spark ignition engine is used for validating total particle numbers at different engine operating conditions. The simulation results agree reasonably with the experimental results. Both experimental and predicted results showed that the inception rate increases with the engine load in an exponential form. The model has a tendency to over-predict the soot in the nucleation phase and under-predict the engine out particle numbers.