It happened just before noon on Route 70 in Southampton Township, Burlington County.
According to the New Jersey Attorney General's Office, the on-duty state trooper was conducting routine patrol duties on Rt. 70 when his marked vehicle collided with a motorcyclist on the highway near Burrs Mill Road.
The motorcyclist was transported to Virtua Mount Holly Hospital, where he was pronounced dead at approximately 12:45 p.m.
Authorities say the state trooper did not sustain significant injuries.
The motorcyclist has not been identified.