The present invention relates to a catalysis apparatus for testing catalysts with variable process pressure adjustment over a pressure range from 0.01 millibar to 300 bar. The apparatus preferably has a plurality of reaction chambers (101, 102, . . . ) arranged in parallel, the reaction chamber outlet-side lines (211, 212, . . . ) of which are divided into two groups of sub-lines. One group of main lines (411, 412, . . . ) is operatively connected to a regulating valve (61), which is common to all of the main lines, and to an exhaust-air line (62), and the second group of secondary lines (311, 312, 313, . . . ) and switching valves (321, 322, . . . ) is operatively connected to an analysis unit (34). It is preferable for reaction chamber outlet-side lines (201, 202, . . . ) to be equipped in each case with a separate line for regulating fluid supply (211, 212, . . . ). In a preferred embodiment, the connecting points of the reaction chamber outlet-side lines (201, 202, . . . ) to the respective main lines (411, 412, . . . ) and secondary lines (311, 312, . . . ) have in each case one mixing vessel (301, 302, . . . ).