Different iron-containing H-ZSM-5 type zeolites have been used as catalysts for the coupled methanol-hydrocarbon cracking (CMHC) process with n-butane as hydrocarbon feed. Furthermore, these iron-containing zeolites (synthesis: silicon-to-iron ratio = 15 : 150 and silicon-to-ironto-aluminium ratio = 50 : 1: 1) have been investigated as catalysts in the well-known MT0 (methanol-to-olefin) process and in n-butane pyrolysis, the two single reactions of the coupled process. In methanol transformation into olefins at 673 K silicon-iron catalysts showed a high activity (nearly 100 wt.-% methanol conversion) and a C,-C, olefin selectivity of about 60%. In comparison, only silicon-aluminium-containing H-ZSM-5 type zeolites showed a decrease in olefin selectivity and more aromatics and liquid hydrocarbons were obtained. In n-butane pyrolysis silicon-iron zeolites have a lower activity compared with silicon-aluminium catalysts By incorporating aluminium into silicon-iron zeolites the activity in pyrolysis could again be increased. In the CMHC process the low activity of silicon-iron catalysts in hydrocarbon pyrolysis led to a low nbutane conversion and to a low amount of olefins formed, but the lifetime of the zeolites used was increased considerably in comparison with silicon-aluminium-containing zeolites. Furthermore, a lower deposition of coke was observed connected with a higher amount of carbon oxides, in particular carbon dioxide, during the reaction. Hence, the hydrocarbon conversion, the olefin amount obtained and the catalyst life could be increased by using silicon-iron-aluminium zeolites in the CMHC reaction.