The process of selective oxidation of o-xylene in a tubular reactor over a vanadia-titania catalyst (V2O5/TiO2) with the catalyst thermal deactivation have been described by means of the Langmuir-Hinshelwood kinetics, while the Erofeev equation for the catalyst deactivation was adopted. On the basis of the model, the kinetic constants have been calculated for eight oxidation reactions from the substrate to the products. Moreover, the catalyst deactivation constants have been determined. The calculation results predict correctly measurements data for the process in the tubular reactor.