A process for producing natural gas hydrate comprises three states (i), (ii), and (iii). State (i) comprises three pressure vessels (A1, A2, and A3), stage (ii) two pressure vessels (A4 and A5), and stage (iii) the pressure vessel (A6). The conditions of temperature and pressure in the pressure vessels are such that the gas hydrate is formed in the vessels. The formed hydrate is taken off through pipes (e1, e2, e3, e4, e5, and e6) from the pressure vessels to a manifold (34). Chilled water which is both the reactant water and coolant for the process is provided by cooling means (20) and supplied simultaneously to the lower part of each pressure vessel via pipe (22), manifold (32) and pipes (b1, b2, b4, b5, and b6). Natural gas from supply (26) is fed via pipe (30), manifold (32) and pipes (c1, c2, and c3) to nozzles in the lower part of each vessel (A1, A2, and A3) from which nozzles the gas bubbles upwards through the columns of water in vessels (A1, A2, and A3). Unreacted gas is fed from vessels (A1, A2, and A3) to similar nozzles in the vessels (A4 and A5) from which unreacted gas is fed to a nozzle in the vessel (A6) from which the unreacted gas is taken off through pipe (d6). The mean upward superficial velocity of the gas is substantially the same in all three stages.