BACKGROUND Nimesulide (NIM), a nonsteroidal anti-inflammatory drug (NSAID) acts as an antipyretic, analgesic and anti-inflammatory agent, and it is widely used in treating acute pain due to various diseases such as headache, migraine, back pain and postoperative pain. Nimesulide is reported to have poor solubility in water (0.01 mg mL(-1)). In this work, the solvent-antisolvent (S:AS) precipitation of NIM using spinning disc reactor (SDR) was investigated. RESULTS Comparative studies were investigated between stirred tank reactor and SDR. The effects of different functional parameters of spinning disc process such as S:AS ratio and flow rate, nimesulide concentration, disc surface texture, capping agent concentration, different capping agents and speed of rotating disc were studied on the particle size of nimesulide. The average particle size of 192 nm for nimesulide was successfully achieved with a considerable particle size distribution at a 300 mL min(-1) total flow rate, with the following parameters: concentration of nimesulide in ethanol 0.5 mg mL(-1); concentration of polyvinylpyrrolidone (PVP) in deionized water 1 mg mL(-1); S:AS ratio 1:6 and at 3000 rpm rotating disc speed. This result should be compared with 9.5 mu m particle size with mechanical agitated contactor at S:AS ratio 1:6 and speed of agitation 600 rpm. CONCLUSION The NIM nanoparticles can be continuously prepared in a SDR with a control and uniform particle size. This leads to increased dissolution rate and bioavailability of poorly water soluble drugs. (c) 2018 Society of Chemical Industry