The final phase of the £35m restoration of the Grade II-listed Leeds Grand Theatre is coming to a close and the venue will reopen on 16 January 2009.

The second phase of the project, called Transformation, has involved the restoration of The Howard Assembly Room, adjacent to the Grand Theatre, and its conversion into a 350-seat performance space by contractor Lang O’Rourke. The assembly room was originally used as a debating hall, entertainments area and had a short spell as a 'gentleman's cinema', before closing 20 years ago due to disrepair.

Dominic Gray, director of projects at Opera North, says: “The assembly rooms mean we can start programming and researching other types of music, so it’s not just about opera but contemporary music, music theatre and music from other ethic origins.” The new venue will provide an unusual space for social and corporate events, as well as a place to nurture young performers and to host the work of new artists and music events.

The Howard Assembly Room will also act as a rehearsal space for the orchestra of Opera North, the northern national opera company, which will set up a permanent home at the Grand Theatre following completion of Transformation. During phase two, which cost £11m, the Grand Theatre acquired three new music coaching suites and link bridges connecting the theatre's new stage door entrance with Premier House – the headquarters of Opera North. The Grand Hall has been refurbished to include a bar and hospitality area, which links the main auditorium with the assembly room.

Phase one included large-scale improvements to the auditorium seating and air cooling as well as the upgrade of the performance areas. Funding for the scheme has come from partners including Arts Council England, the Heritage Lottery Fund, Leeds City Council, Yorkshire Forward, Leeds Grand Theatre, Opera North and the Opera North and Leeds Grand Theatre Development Trust.

Andy Carver, executive director of Arts Council England, Yorkshire, said: "The redeveloped theatre and assembly room will enrich the cultural life of the city and the region, giving many more people the opportunity to experience great art and performances. "It also marks a new phase in the life of Opera North, as they now have a permanent base in an opera centre."