Southern rail is to reinstate more than a third of the 341 daily services it axed earlier in the summer to provide a more reliable timetable.
The 119 trains, nearly all in London, will run from 5 September.
The operator introduced a reduced service in July after months of delays and cancellations, which it blamed on "unprecedented" staff sickness.
Southern is in a long-running dispute with its guards and the latest 48-hour strike begins on 7 September.
The reinstated trains include:
- All of its "metro" services in south London
- Sutton to Streatham via Wimbledon
- Twenty-six services on the West London line between Clapham and Watford Junction/Milton Keynes
- Guildford to Leatherhead
Southern said it planned to "steadily" bring back further services, for Sussex and Surrey, in the coming weeks as train crew became available.
The RMT rail union is fighting moves to turn conductors on Southern into "on-board supervisors", with drivers taking over responsibility for opening and closing carriage doors.
The union has said it has concerns over safety and job cuts, but the company began imposing the changes earlier in August.