A Chartered Accountant and Company Secretary by professional qualification, Purkayastha was Executive Director (Finance & Accounts) in GAIL before being elevated to the Board, the company said in a statement here.
He replaces P K Jain, who superannuated yesterday.
Purkayastha, 56, is also Director on GAIL Gas (USA) Inc, Ratnagiri Gas and Power Pvt Ltd (RGPPL) and TAPI Pipeline Co Ltd.
"He joined GAIL in 1985 as a Finance Officer and rose to the position of Executive Director," the statement said.