TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Catalyst: The support is a Group III or IV metal oxide, especially alumina, silica or zirconia, and is present in an amount of 50-95% by weight of (I). (II) is a Group VIII metal, especially palladium or platinum, and is present in an amount of up to 3 wt.%.Preferred Process P1: Heat treatment is effected for up to 15 hours. The support has a particle size of up to 200 microns. The halocarbon is present in an amount of up to 10 wt.% and is introduced by adsorption at up to 200degreesC for up to 5 hours.Preferred Process P2: A halogen-containing promoter is added to the feed in an amount of up to 0.1 wt.%. The feed is a C5+ paraffin or cycloparaffin fraction and isomerization is effected at up to 200degreesC and up to 50 atmospheres with a feed rate of up to 10 kg per kg of catalyst per hour in the presence of up to 80 mole% of hydrogen, and the feed contains no more than 0.01 wt.% water or oxygenates, no more than 0.15 wt.% combined sulfur and no more than 0.0005 wt.% nitrogen compounds or alkaline compounds. The feed is n-butane or n-pentane and isomerization is effected at up to 170degreesC and up to 35 atmospheres with a feed rate of up to 10 kg per kg of catalyst per hour in the presence of up to 5 mole% of hydrogen, or the feed is n-hexane or cyclohexane and isomerization is effected at up to 150degreesC and up to 35 atmospheres with a feed rate of up to 10 kg per kg of catalyst per hour in the presence of up to 5 mole% of hydrogen. EXAMPLE - A mixture of gamma-alumina (100 g), water (500 ml) and acetic acid (1 ml) was treated dropwise with a solution prepared by dissolving palladium chloride (0.634 g) in concentrated hydrochloric acid (3 ml) and diluting to 18 ml with water. The mixture was stirred for 1 hour, decanted, dried at 130degreesC for 3 hours and calcined at 750degreesC for 2 hours. The product (89 g) was treated with a solution (70 ml) containing 96% sulfuric acid (19.5 g) in water and then air dried, dried at 200degreesC for 1 hour and calcined at 500degreesC for 2 hours. The product (3.2 g) was placed in an isothermal microreactor, which was supplied with hydrogen at 145degreesC for 1 hour, then supplied with hydrogen containing carbon tetrachloride (10 mul) at 145degreesC for 15 minutes, and then supplied with a mixture of n-hexane (containing 10 ppm carbon tetrachloride) and hydrogen at 145degreesC and 15 atmospheres, with a hydrogen/hexane molar ratio of 0.07 and a feed rate of 4 kg/kg.hour. The n-hexane conversion was 88% with 99.1% selectivity for C6 isomers. The product contained 41.3 wt.% dimethylbutanes and 29.3 wt.% 2,2-dimethylbutane.