Ian Thuaux will be celebrating his 19th birthday in unusual circumstances for a Sydney teenager, following a sincere desire to do short-term mission to the other side of the world.

On the 27th of July he will wake up a year older " and a member of an evangelistic mission to Kenya, with six other members of the Youthworks Camping Division.

"I'm not going to project Christianity on to them," he says. "I'm going to share what I believe myself."

A total of 22 Sydneysiders flew out from Mascot on Friday with five volunteers from Melbourne and two more from New Zealand.

They will join an international contingent of 120 youth and 200 Kenyans witnessing in Nairobi.

Parents Janine and David will miss marking the milestone with Ian, but they respect the way their son has chosen to spend it.

"I'm a bit sad," says Mrs Thuaux. "But Ian's adventurous and it's a great way to celebrate a birthday."

And rather than receiving presents, Ian will spend the next four weeks handing them out.

His team is transporting 180 kilograms of soft toys, soccer balls and scripture material " amongst other things " to give to Nairobi's most disadvantaged children.

African Enterprise ministry developer Peter Gunning says it has been a privilege to prepare this team of teens for the past six months.

He expects their short mission to have an enduring effect.

"The perfect result from this trip would be for them to all come back safe and sound with a clear understanding of the issues behind ministry in Africa," Mr Gunning says.

It will be the first time Ian travels abroad without family, but the prospect of tackling Africa on his own hasn't wiped the smile from his face.

"I just really enjoy sharing my faith," he says, shouldering a bag.

And flanked by his team members, he heads for the gate.