He succeeds K Sivan, who was appointed as ISRO Chairman recently.
Somanath took charge at a function in ISRO headquarters Bengaluru, Vikram Sarabhai Space Centre (VSSC) sources said here.
He is currently the Director of Liquid Propulsion Systems Centre at Valiamala here, the lead centre responsible for liquid engines and stages for all launch vehicles and satellite programs of ISRO, the sources said.
He was the Associate Director (Projects) of VSSC and also the Project Director of GSLV Mk-III launch vehicle.
Somanath joined ISRO in 1985 and was a team leader for Integration of PSLV during its early development phase and during the first flight of PSLV and the successful second flight PSLV-D2, the sources said.