A chemiluminescence (CL) flow-through sensor for the determination of analgin was described. It was based on the direct oxidation of analgin by manganese dioxide to produce a weak CL in the absence of luminescence reagent. The CL intensity in acidic medium was enhanced by the addition of Rhodamine B (RhB). The solid-phase manganese dioxide was immobilized on the sponge rubber inside the CL flow cell by a very simple means. The calibration graph is linear in the range 4×10 −5 to 1×10 −3 g/ml with a detection limit of 2.7×10 −5 g/ml (S/N=3). The sensor was successfully used for automated dissolution testing of analgin tablets and sampling frequency was 120 times/h. The dissolution profiles of analgin tablets from three different plants were obtained, which demonstrate the stability, sensitivity, large dynamic measuring range and robustness of the system.