Montague Alexander Phillips (1 December 1902 - 12 October 1972) was an English industrial chemist and chemical engineer.

He is notable for the synthesis of the drug sulphapyridine in 1937, while working as a research chemist at May & Baker, Dagenham, Essex. Sulphapyridine (also known as sulfapyridine, T693, M&B 693 and Dagenan) was an early antimicrobial/antibiotic and the first effective treatment for pneumonia, meningitis and various other bacterial infections of humans and animals. As such, it saved many tens of thousands of lives globally in the years before penicillin and other antibiotics became generally available.

In the 1960s, Phillips was a key whistleblower in the thalidomide scandal.

Phillips attended the John Roan School, Greenwich. At 18 he joined May & Baker, Battersea as a laboratory assistant while taking evening classes at Battersea Polytechnic. He graduated with a Bachelor of Science (BSc) degree in Chemistry in 1926. In 1942 Phillips was awarded a Doctor of Science (DSc) degree by London University.

In addition, Phillips was a Fellow of the Royal Institute of Chemistry (FRIC), Chartered Member of the Institution of Chemical Engineers (MICHemE), Chartered Chemical Engineer, Chartered Engineer (CEng), Fellow of the Royal Society of Medicine (FRSM) and Fellow of the Chemical Society (FCS).

The drug Prontosil was introduced in 1935 by IG Farben, Germany as an antibacterial treatment for streptococci infections. Later that year, Daniel Bovet at the Pasteur Institute, Paris determined that sulfanilamide was the active form. These were the first of the so-called sulfa drugs and their advent represented a revolution in the treatment of infectious diseases through drug therapy. Within months, a number of other pharmaceutical companies began efforts to develop their own antimicrobials.

In early 1936 the UK chemical company May & Baker commenced an extensive search for new sulfanilamide derivatives with useful antimicrobial properties. This project was initiated by Arthur Ewins (director of research) and carried out by chemists George Newberry and Montague Phillips. Since May & Baker lacked suitable facilities, animal testing was conducted through a collaboration with Lionel Whitby, then a clinical pathologist at the Bland-Sutton Institute of Pathology, Middlesex Hospital in London. Between May 1936 and November 1937 around 64 different sulfanilamide compounds were synthesised and evaluated.

The synthesis of sulphapyridine was not planned but rather it was produced opportunistically due to the availability of aminopyridine, a chemical precursor. The first sample of sulphapyridine was created by Phillips on 2 November 1937. This comprised 10 grammes and was initially recorded in the May & Baker laboratory test log as T693. The log entry was also initialed by Phillips. The final synthesis step, which involved the removal of an acetyl group, was not straightforward. The standard technique, using hydrochloric acid, does not work in this particular case. Instead, Phillips devised a counter-intuitive approach using sodium hydroxide. A few grammes of the first sulphapyridine sample were delivered to Whitby for animal testing with the designation M&B 693.