A six-month-old baby has d!..ed after being left in a hot car for seven hours.

Travis Carter Jr was found in the back seat of a neighbour’s car after they allegedly forgot to drop him back with his father.

He was pronounced d£.ad by paramedics when they arrived at the scene at about 9pm on Tuesday, July 30, in Cordes Lakes, about 60 miles north of Phoenix, Arizona.

The neighbour, a teenager, was arrested and charged with negligent homicide.

Earlier that day, Travis’s mother Aleesia Phillips asked the teen neighbour to drive her to Prescott Valley.

She took Travis with her, but after the baby fell asleep she asked the neighbour to drop him at his father’s house when she went to work.

The neighbour arrived home around 2pm but didn’t take the baby to dad Travis Carter’s house next door.

Instead they "parked the car exposed in the hot sun and went into their house, claiming to forget about the baby in the car," police said.

Travis called Aleesia about 8.45pm to ask what time the neighbor would be dropping off Travis.

Aleesia immediately called the neighbor to find out what was going on, and only then did they realise the baby was still in the car.

After realising that they had forgotten about the baby, "the neighbour ran next door to the father’s house and both the father and neighbor pulled the baby out of the car, called 911 and tried CPR," police said.  

The neighbour was charged as a juvenile on Thursday, August 1, and therefore hasn’t been named.