The infant also died in the incident.
Rinki was not in good relation with her husband Mahaveer and today morning they had an argument over some petty issue, said Gorakh Nath Yadav, SHO of Loni police station.
After Mahaveer left for work, Rinki took her infant son in her lap and set herself on fire after pouring kerosene, he said.
The bodies have been sent for post mortem examination and a probe is on.