The Bowland Explorer will connect with Bentham Line rail services from Leeds and Morecambe at Bentham station, on Sundays from May7 until September 24.
At the other end of its route the Bowland Explorer will connect with Clitheroe Line rail services to and from Manchester, Bolton and Blackburn (connections for Preston).
The service will also operate on Bank Holiday Mondays in late May and August.
The buses start from Lancaster Station early on Sunday mornings to provide a service between Lancaster and Bentham via Caton, Hornby, Wray and Wennington station before commencing Bowland duties. Full details will be available from mid-April at stations and tourist information centres or by telephoning 015242 98940.