Police were called to the service station shortly after 11pm.

The man, who was wearing dark jeans and had a maroon coloured T-shirt around his head, allegedly entered the service station and threatened a 24-year-old female staff member with a baseball bat.

He allegedly struck the front counter and a counter display with the bat, smashing the display and scattering confectionary over the floor.

Police said, the man, who was given a small amount of cash and cigarettes, also struck the glass doors a number of times with the bat as he was leaving the premises.

The female attendant was shaken but uninjured in the robbery.

Police were on the scene moments after the hold-up but the man, who had arrived on foot, fled across the highway and into bushland near the entrance road to the Flinders Industrial Estate.

Police searched the bush on the western side of the highway for a number of hours but found no trace of the man.

They also searched nearby Chapman Motors at South Nowra after police received reports the man was seen jumping the fence into the car yard.

Crime scene officers from forensic services and Shoalhaven detectives were at the location into Friday morning examining the scene and gathering evidence.

The incident is the latest in a series of similar armed robberies across the Shoalhaven in the past six months.

Police are hoping CCTV footage from the store may be able to help identify the man.

He is described as Caucasian in appearance, between 160 to 165 centimetres tall with short cropped hair.

Anyone with any information about the robbery is urged to contact Shoalhaven detectives on 44219699 or Crime Stoppers on 1800 333000.