The aim of this paper is to study the kinetic effect of hydronaphthalenics on the thermal cracking of alkanes and to demonstrate that tetralin can be employed as a model compound of the hydronaphthalenic fraction derived from a specific resinite (Dammar resin) present as structural subunits of asphaltenes in petroleum of southeast Asia and Australia. Indeed, Dammar resin and tetralin were pyrolyzed in the presence of n-hexadecane (nC(16)), at 330 degrees C under 70 MPa for time periods from 72 h to 1 week. In both cases, significant inhibition of the cracking of the nC(16) was observed. A previous reactive network model for the nC(16)-tetralin mixture [from Bounaceur et al., Ind. Eng. Chem. Res. 2002, 41 (19), 4689-4701] was adapted and improved on the basis of our new experimental data. It includes 226 free-radical reactions and 1 molecular reaction (retroene reaction). The formation of the main products-namely, alkanes, alkenes, 1-methylindane, and butylbenzene-is correctly described by the model. The kinetic model allows direct extrapolation of the hydrocarbons mixture behavior to geological temperatures (200 degrees C). A geochemical parameter that measures the kinetic effect (inhibition or acceleration) of one compound on the others in complex mixtures was calculated; this parameter is called the inhibition factor (IF). The IF increases strongly when the temperature decreases from 375 degrees C to 200 degrees C, whereas it decreases when the temperature decreases from 500 degrees C to 375 degrees C. The presence of this minimum in the IF-versus-temperature curve is surprising, and an explanation of this behavior can be suggested: it is probably the result of the competition between new initiations (with butylbenzene and other products), which lead to acceleration, and new terminations (with resonance-stabilized radicals), which lead to inhibition. Tetralin behavior is compared to decylbenzene, which is another n-alkanes cracking inhibitor. The effectiveness of each inhibitor differs as the thermal cracking proceeds. The main conclusion for the petroleum geochemistry field is that n-alkanes stability is greatly enhanced by hydronaphthalenics and, therefore, also by Dammar resin in petroleum reservoirs. Some arguments, mechanisms, and conclusions could also be extended to the improvement of jet fuel thermal stability, as an example. Therefore, this paper might interest readers from parallel fields.