A biofilter of 0.05m diameter and 0.58m height has been studied for the removal of styrene from a simulated air-styrene mixture through the microbial route using Pseudomonas putida. Coconut coir and other waste materials have been used as the immobilization matrix for the microorganisms. Gas flow rate (0.005-0.01kgm-2s-1), micronutrient liquid flow rate (5-10 kgm-2s-1), inlet styrene concentration (0.05-1.20 gm-3) and packing size (de = 0.08 - 0.18cm) have been used as parameters. The kinetic parameters of growth rate equation of bacterial strain have been determined using batch type experimental data. A Monod type reaction model has been observed to be appropriate for the explanation of growth kinetics of the microorganisms. The values of the kinetic parameters used are Ks = 0.8gm-3, µmax = 45h-1. A three-phase deterministic mathematical model has been developed incorporating the synergistic effect of simultaneous reaction and interphase (gas to liquid to biofilm) mass transfer of styrene using experimentally determined kinetic parameters and mass transfer coefficients calculated using standard correlations. Simulated results based on the model have been compared with the experimental ones satisfactorily.