Abstract: Conversion of the synthetic gas mixtures: carbon monoxide - hydrogen or carbondioxide - hydrogen is carried out in the presence of a catalyst constituted by the association of at least two transition metal elements with an acitve mordenite selected from among de-aluminized acid mordenites. The metal elements can be copper, zinc and chromium. The transition metal elements - active mordenite association can be employed in separate catalytic beds, the first bed being metallic in nature and the second zeolitic in nature. The process is applicable to the manufacture of organic products such as saturated and unsaturated hydrocarbons, particularly light olefines.