Semenov was born in Saratov in Russia and educated at the University of Petrograd (now St. Petersburg). After working in various institutes in St. Petersburg he moved to Moscow University in 1944 as head of the department of chemical kinetics.

It was for work in this field that Semenov was awarded the 1956 Nobel Prize for chemistry, the first Russian to be so honored. He shared the prize with Sir Cyril Hinshelwood. His particular contribution was in the study of chemical chain reactions – an idea introduced by Max Bodenstein in 1913. Semenov investigated the idea of a chain reaction in the 1920s and was able to show that such reactions can lead to combustion and violent explosions when the chain branches, spreading with explosive rapidity. In 1934 he published a book on the subject, which was translated into English the following year, Chemical Kinetics and Chain Reactions.