In this work, the catalyst deactivation phenomenon in the case of special hydrocracking of sunflower oil and kerosene mixture was analyzed based on experiments and models. Alternative (bio/waste-originated) fuels are becoming more important to reduce the full life cycle environmental pollution of transportation. One of the production possibilities of these alternative fuels is the co-processing (i.e., catalytic quality improvement) of fossil and biobased feedstocks. The huge number of individual chemical components in the system increases the complexity of the investigation. Moreover, from the chemical analysis viewpoint, only some of these can be followed during the experiments. Hence, the models to describe the processes in this system (hydrocracker) are usually based on lumps (i.e., component groups). Experimental data are reported on the special catalytic hydrocracking of sunflower oil and kerosene mixture for the production of high-quality aviation fuel (JET). Experiments were carried out in a fixed-bed tubular reactor over temperatures between 533 and 613 K, pressure ranging from 30 to 70 bar, and liquid hourly space velocities of 1.0 and 2.0 h(-1), employing a Pt/H-mordenite catalyst. The objective of our work is to investigate the existing lumped models that are suitable for describing the experimental data; moreover, while maintaining the possible reaction pathways, model parameters were identified and validated against the measurements. As a result of the analysis of the measurement data, it has been established that in the case of lower liquid load/higher residence time, a deactivation phenomenon, the so-called catalyst fouling, takes place on the applied catalyst. Three catalyst deactivation models were developed and integrated into the kinetic model: the Levenspiel deactivation kinetic model, a simplified Eley Rideal mechanism, and the last one based on competitive adsorption.