The German shepherds were found in the car at Notts Police's HQ in Arnold yesterday.
The Post understands the police dog handler was off duty but had called into the headquarters at Sherwood Lodge, Arnold.
It is unclear how long the dogs had been left in the car on what was the hottest day in Notts for three years – with temperatures rising to 29.3 degrees celsius.
The RSPCA has launched an investigation into the incident.
A spokeswoman from the charity said: "We are investigating two dogs which have died in a hot car.
Under the Animal Welfare Act 2006, anyone found guilty of causing unnecessary suffering to an animal can face up to six months in prison or a fine of up to £20,000.
A Notts police spokesman said: "Nottinghamshire Police reported the death of two German shepherd police dogs to the RSPCA on Tuesday, June 30, after they were discovered at force headquarters at 2.15pm.
The spokesperson said the force could not confirm any further details about the incident, but said no one had been suspended.
Notts Assistant Chief Constable Peter Davies said: ''This is a tragic incident and we value the important work our police dogs carry out on a daily basis. That is why we swiftly reported this incident to the RSPCA and we will be working with them very closely."
"The RSPCA has been informed and will, I am sure, carry out a thorough and speedy investigation.