The invention relates to a method for producing chlorine by oxidising hydrogen chlorine in a gaseous phase by means of a gas flow containing molecular oxygen and in the presence of a fixed bed catalyst. Said invention is characterised in that the inventive method is carried out in a reactor (1) comprising a bundle of parallel contact tubes (2) disposed in a direction of the reactor length whose ends are fixed to a tube plate (3), a convex cover (4) arranged on each end of the reactor (1), one or several annular deflecting sheets (6) which are arranged in a perpendicular direction with respect to the direction of length of the reactor in a space (5) between the contact tubes (2) in such a way that circular passage openings (8) are formed in the middle of the reactor. The inventive reactor also comprises one or several deflecting discoidal sheets (7) disposed in such a way that annular passages (9) are formed on the edge thereof, said deflecting annular (6) and discoidal (7) sheets being arranged in an alternate manner. According to said invention, the contacting tubes (2) are filled with the fixed bed catalyst, hydrogen chlorine and the gas flow containing molecular oxygen are channelled from one end of the reactor to the contact tubes (2) by means of one of said convex covers (4), a reaction gaseous mixture is extracted at the level of the opposite end of the reactor by means of the second convex cover (4) and a fluid heat-exchanging agent is channelled to the interspace (5) encompassing the contact tubes (2).