Apparatus and a method are described for investigating polymorphs of a material, isomers of a material which allow different isomeric forms to be resolved, different hydrates/solvates and/or different salts of a material. The apparatus comprises an assembly (2) of reactor devices (6) arranged within a reactor body (8) which incorporates a heating/cooling block (10) and a stirrer block (12). A vessel support block (14) supports respective sample vessels (15) below each reactor device (6) for receiving material from the reactor devices. The apparatus includes a control unit (4) which includes a computer (16) which controls a robot for delivering materials to the reactor devices; a heating/cooling unit (18); a stirrer control unit (20); and a pressure unit (22) which controls the passage of material from the reactor devices (6) to the sample vessels (15).