The move is to replace drivers leaving the company and reduce its dependence on overtime to run trains, which caused two months of disruption this summer during a pay dispute,
A total of 74 ScotRail drivers retired or moved to other train operators last year alone.
The recruits will be chosen from among hundreds in a “talent pool” created after ScotRail was swamped with more than 9,000 applications in its last recruitment campaign.
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ScotRail said: “The shortlisting process has identified 845 who remain in the talent pool and will be used for upcoming vacancies.”
A previous recruitment drive in 2015 generated more than 22,000 applications for 100 jobs.
ScotRail has 1,180 fully qualified drivers – 91 of them female.
However, the total is only 12 more than the 1,168 in December, despite 70 trainees qualifying so far this year.
The Scottish Government-run operator said its numbers were expected to remain "relatively stable” for the rest of the year, during which a further 35 drivers are due to qualify.
They are among 125 trainees undergoing training, which takes 18 months.
ScotRail said the training process was back up and running after being severely hampered by Covid because social distancing requirements meant a trainee and a trainer could not be in a train cab together.
Following a 5 per cent pay deal last month, fully-qualified ScotRail drivers’ basic pay increased to £55,264 year.
The train operator said it had set a target of eliminating the need for drivers to volunteer for overtime and work on “rest days” to run services, especially on Sundays, by 2027.
Many drivers stopped working overtime during the pay dispute, with ScotRail forced to temporarily cut up to 700 trains a day, with Sunday services halved.
ScotRail said the pay deal included “a commitment to bring Sundays into the working week within a five-year period with full implementation by the 2027 December timetable.”
The operator said that would require a review of terms and conditions with union officials.
A ScotRail spokesperson said: “Driver training has been progressing well following the delays experienced during the Covid pandemic.
"We plan to recruit 135 trainee drivers over the coming months, and the first of these will start their training in the autumn.
“We currently have 1,180 qualified drivers and we expect this number to remain relatively stable for the remainder of the year, taking into account new drivers qualifying and forecasted attrition.
"Drivers leaving for other train and freight operating companies are included in our forecasted attrition, but this is something that’s very difficult to predict as it’s dependant on the recruitment of these firms.”
Scotland secretary Kevin Lindsay said: “The present timetable does not deliver the service level that the people of Scotland deserve.
"We will continue to work with ScotRail to deliver driver training and work towards getting service levels back to pre-pandemic levels.
"ScotRail has ambitious plans for more drivers and we will encourage them to recruit more from under-represented parts of society.”