When heating paralhn wax in an autoclave in the presence of high pressure hydrogen at 460Β°C during one hour as described below, approx. 80% by weight of thii wax is converted into hydrocarbons boiling below 100Β°C. 2. Under identical conditions but in the presence of hydroipxmtion catalysts the conversion into lower hydrocarbons was far more pronounced. For instance, by the use o? tungsten dlsulphide as hydro8enation catalyst even 75% by wei8ht of the wax wus converted into hydrocarbons boiig below 100Β°C. Moreover the quality of the reaction products was different. In the experiments in the presence of hydrogenation catalysts these products were far more or completely saturated and the formation of cyclic compounds was very low in comparison with the products of hydrogenatlon without a catalyst. Tht catalysts used were : nickel on guhr (i.e. kiese&uhr), tungsten disulphide, colloidal molybedunum on active carbcn and molybdenum trioxde. 8. By the use of SiO,-AlaO, cracking catalyst under otherwise identical conditions conversion into lower hydrocarbons was also increased as compared with the experiments mentioned under 1. The products, however, were more unsaturated but they contained about the same amount of rings per molecule, that is approx. O-8. 4. By the use of mixed type catalyst the conversion as well as the quality of the products were between those of the experiments mentioned under 2 and 8. IMum&-1. Par cbauffage B 430Β°C de la parafllne solide en presence d'hydrog&ne sous haute pression, les auteurs en ant trtmfomd 80% environ en hydmcarbures, bouillant au dessous de 100Β°c. 2. Dans les m&nes conditions, mais en p&ence de catalyseurs d'hydro&nation, le craquage est beaucoup plus accent& par example, avec WS,, 75% de la parafllne sont convertis en prod&s boulllant au dessous de 100Β°C. L'emploi de catalyseurs d'hydro#natlon modifie b la fois le rendement et la qualiti dew pmdults. Ceil demiers sont enti&rement ou presque totalement natures, la production de prodults cycliques devenant t&a faible. Catalyseurs essay&s : nickcl, \ sulphure de tun@&ne, molybdene collo@al sur cbarbon actif, trioxyde B molybdene. 8. En presence de SiOpAl,O, comme catalyseurs, le craquage est plus accent& qu'en emai 1, les produits obtenus sont mains satur& tout en conservant approxlmativement la m&me proportion d'anneaux par molecule. (O-8 environ). 4. Un eatalyseur mixte donne des. rdsultats lnterwn%ahw entre ceux qui correspondent aux essals2et8.