'I've never felt so much relief as when I saw police waiting for me': Sydney siege hostage

An 83-year-old man, who was held hostage at Sydney's Lindt cafe, has spoken publicly about the harrowing 16-hour ordeal.

John O'Brien, 83, who was held hostage at Sydney's Lindt cafe, is the first hostage to publicly speak out about the harrowing 16 hour ordeal. (Screenshot)

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After a Monday morning appointment with the eye doctor, John O'Brien, 83, was having a quick coffee in the Lindt cafe in Martin Place when things took a turn for the worst.

A 50-year-old gunman, self-styled Iranian cleric Man Haron Moris, walked into the cafe and held 17 people hostage, including cafe employees and customers.

More than 16 hours later, two hostages, Tori Johnson and Katrina Dawson, and the gunman were dead.

"All I was doing on that Monday morning was going down for a quick coffee at the Lindt coffee shop, having gone to the eye doctor for an eye check-up," Mr O'Brien told reporters.

"I've never felt so much relief as when I turned that corner and saw armed police waiting for me."

Mr O'Brien added that he was grateful to be home with his wife, thanking the NSW Police for their work, as well as the public for their kindess and support.

He also paid his respects to the two victims of the siege.

"I would like to pay tribute to Katrina Dawson and Tori Johnson and offer my heartfelt condolences to their friends and families."