The explosion happened in the eleventh-floor apartment on Tantogatan, in the Södermalm district of the capital, just after 11 am on Saturday.
“The man was taken to the Södersjukhuset hospital, where he died,” police spokeswoman Marie-Louise Nilsson said.
The fire brigade was alerted to the explosion at 11:06. Around 25 firefighters were sent to the scene. The fire was successfully contained in the apartment. The man was found in the flat and was taken away by firefighers.
The stairwell of the building filled with smoke, but firefighters said they had not needed to evacuate the whole building.
“We checked the apartments on the ninth and tenth floors to make sure that nobody was still there,” said Dan Petersson of Stockholm fire brigade.
The cause of the fire has not been established, although police believe it could have been caused by an exploding television.
The dead man has not yet been positively identified, but a 56-year-old man lived in the apartment.