The encounter took place at around 5 am when Assam Rifles personnel spotted militants planting Improvised Explosive Device (IED) at Chamol village, 18 km from Chakpikarong police station, a senior police officer said.
A gunbattle followed in which the unidentified militant was killed and two Assam Rifles jawans were injured, the police officer said.
A rifle and three unexploded IEDs were recovered from the site by the Assam Rifles troopers, he said.
On Monday, two Assam Rifles jawans were killed and six others were injured when militants exploded a powerful IED at Man Mani village in the same district, following which security had been strengthened.
Banned insurgent outfit Revolutionary People's Front (RPF) had claimed responsibility for Monday's attack.