He fired two shots at his 45-year-old Venezuelan wife. One bullet hit her in the hip and one in the stomach.
She ran out of the house calling for help and her husband then turned the Smith & Wesson gun on himself, and died soon after. Neighbours quickly called the police.
The drama unfolded in the couple's home in Vienna's Favoriten district early on Tuesday morning.
The elderly man was Austria's former ambassador to Venezuela. His name has not yet been released.
He met his wife, 37 years younger than him, when she worked for him as a housekeeper and cook. When his posting came to an end, around 20 years ago, she returned to Austria with him and they married.
The man may have acted in a jealous rage, the Austrian Press Agency reported. Neighbours said that the couple often fought.
One neighbour said the 82-year-old was very smart, polite, and he wrote books. "But when it came to women he wanted to control someone," the neighbour said.
He described the wife as very friendly and sociable, and said that she did all the work around the house - including carrying crates of beer and taking care of the couple's car.
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Police spokeswoman Adina Mircioane said the woman had emergency surgery early on Tuesday and was now in a stable condition.
The deceased man has an adult son.
He was previously Austria's ambassador to Colombia and made the news when he was taken hostage with other diplomats by the M-19 guerilla group in Bogota. He was released earlier than his colleagues as his then-wife was seriously ill in hospital.