More than 20 Red-tailed Phascogales are set to be released in a national park in NSW after a 450-kilometre journey from a breeding program at Adelaide Zoo.

To mark World Wildlife Day, the 11 females and 10 males will be released on Friday night into a fenced area of the Mallee Cliffs National Park, in the NSW Sunraysia region.

They will add to the population of 93 released into the national park over the past two years with the tiny mammals previously considered locally extinct.

Zoos SA's Conservation Coordinator Lisa West said each animal had been fitted with a collar to allow their transition to their new environment to be monitored.

"That will give us vital information into their movements and behaviour," Ms West said.

The collars are designed to break off in four to six weeks.

The Red-tailed Phascogale was once found across most of arid and semi-arid Australia, however, they now occupy just one per cent of their former habitat.