Abstract: A vertical reactor for catalytic exothermic and endothermic reactions, especially for the production of methanol, ammonia, synthesis gas and higher alcohols, with a jacket containing the catalyst bed and exchanger pipes which form a tube bundle running through the jacket parallel to its longitudinal axis, with a gas-permeable floor supporting the catalyst bed, as well as feed and discharge pipes for the cooling or heating medium running through the jacket lid and the jacket floor, said feed and discharge pipes, as well as feed and discharge pipes for the reaction gas, leading into horizontal distributing and collecting pipes wherein the upper and lower ends of the upright or essentially upright exchanger pipes of the tube bundle lead into horizontal supporting headers which are parallel to each other and arranged below and above the collecting and distributing pipes.