Abstract Introduction: Formaldehyde is a toxic, mutagen and probably carcinogen compound that can be released to air by world different industries. The present study aimed to investigate the kinetic parameters of a trickling bio-filter as well as to present a simple regression model. Methods: The data of previous studies on formaldehyde vapor removal by bio-trickling filter in a laboratory scale was used to determine rmax and Km. Moreover, the data were applied to develop a simple regression model. Results: Formaldehyde removal efficiency in different input concentrations was predicted by both regression and kinetic models. All results were compared with actual data in the pilot study. Conclusion: The results of the present study revealed that although regression model has a high precision, it only could predict the mean of bio-filter efficiency in formaldehyde removal. Kinetic model demonstrated some extent of error in predicting, though it has a good alignment with the actual data, and thus, the results of this model can approximately predict ups and downs of system navigation.