Biofiltration is a cost-effective technology for reduction of odor emissions from intensive pig production, but removal of volatile sulfur compounds may be limited by low mass transfer. Among these volatile sulfur compounds, hydrogen sulfide and methanethiol are essential odorants emitted from animal houses according to the low odor threshold values. In order to get a better understanding of the limitations for optimization and further development of biofiltration for odor control, a study of overall mass transfer coefficients of volatile sulfur compounds for packing materials potentially used for biotrickling filters is presented. Mass transfer coefficients were obtained by taking advantage of online PTR-MS experiments of breakthrough curves, combined with a developed mass transfer model. The experiments were performed at different air and liquid velocities for selected packing materials. The results demonstrate that the overall mass transfer coefficients of volatile sulfur compounds depend on the velocity of both air and liquid. When the mass transfer coefficients are normalized to (divided by) the corresponding pressure drop, the results indicate that the filter packed with ceramic saddles or cellulose pads have higher normalized mass transfer coefficients, compared to the other materials investigated in this study. Correlating the mass transfer coefficients to characteristics of different packing materials did not succeed and as an alternative empirical relationship between mass transfer coefficients and the gas and liquid velocities were established. (C) 2014 Elsevier B.V. All rights reserved.