Boone Pickens, left, surprised his friend Harley Hotchkiss, right, with news of his donation Friday. (CBC)

A Texas oil tycoon, who was being honoured at a University of Calgary luncheon for a past gift, surprised everyone when he announced he's donating $25 million to brain research at the school.

T. Boone Pickens, who has an estimated net worth of $3 billion, used to live in Calgary when he worked as a geologist, but he said the gift is mostly motivated by his longtime friendship with Calgary Flames co-owner Harley Hotchkiss.

Hotchkiss created the brain institute that bears his name with a gift of $15 million in 2004.

"I lived here in the '60s, and it was a very good experience," said Pickens. "Harley and I have been friends so when he asked me to help, I did."

Pickens, 80, had given the Hotchkiss Brain Institute $2.25 million two years ago. The money went to establishing the Boone Pickens Centre for Neurological Science and Advanced Technologies at the facility.

Moments before the centre's official opening Friday, Pickens handed Hotchkiss a letter outlining his $25-million gift — the largest donation ever given to the university by a single person.

"I had no inkling of this at all, none," said Hotchkiss. "He told me when he made the first donation two years ago that he'd watch what we are doing and we might see him again."

Pickens said he has given away $700 million in the last five years, but Friday's donation is the only philanthropy he has done outside the U.S.

Researcher Michael Colicos shares a moment with his daughter Alexandra who has epilepsy. (CBC)

"The good thing about Boone Pickens if you're in something that's challenging, he never bails out," said Hotchkiss about his friend.

The Boone Pickens Centre is already helping researchers at the Calgary university, including Michael Colicos, who is growing living brain cells on silicon computer chips to figure out what goes wrong in neurological disorders.

Using a technology called photoconductive stimulation, he gets the cells to fire by targeting them with light and a short, electrical pulse.

"It's probably in every science fiction film from The Terminator to Star Trek but now that we have the interface part of the technology then it's starting to become more of a possibility," he said.

Colicos's research also has a personal side because his two-year-old daughter, Alexandra, has epilepsy and could benefit from his discoveries.