The northern half of the church transepts was added in 1899. In 1902 a pipe organ was installed, to which an electric blower was added in 1925. In 1909, major alterations to the Mowbraytown church included completion of the second half of the transepts, construction of a new vestry, extension of the nave toward the street, removal of the main doors from the sides to the front, and the addition of an entry porch. Later, two porches with side doors were added to the northern transept. A larger Sunday school hall, adjacent to the church and facing Mowbray Terrace, was erected , on land acquired in 1904 from church elder Alexander Smith Lang. Following the First World War an honour board and memorial pulpit were erected in the church. The building appears to have been re-roofed , with fibrous cement tiles similar to those on the hall. The exterior walls were clad and sprayed in 1966. The leadlight windows at the front of the church were donated by Alexander Brown Wilson, who as church architect had designed the extensions and both halls. Wilson designed several other Presbyterian buildings in Brisbane, including extensions to the Ann Street Presbyterian Church. Following his father's retirement in 1928, Ronald Martin Wilson was appointed church architect. The Mowbraytown Presbyterian Church has played a strong role in the spiritual and social life of East Brisbane. The hall has been the venue not only for church activities, but also for community concerts, ballet and gymnastics classes, meetings and seminars, dances, children's play groups, and polling booths. Both the church and hall are local landmarks, and have featured prominently in heritage walking tours of East Brisbane organised by the Mowbraytown Residents' Association. The Mowbraytown Presbyterian Church group consists of a church, with a small kindergarten room attached at the rear, and an adjacent hall to the east, which are located on a level corner site in East Brisbane. The single-storeyed timber church, with timber buttresses, has been clad with fibrous cement sheeting and sprayed with a rough finish concrete render. The building has a steep pitched gable roof, a twin gable transept, sprocketed eaves, asbestos cement tiles laid in a diamond pattern and a sheet metal spire surmounted by a cross over the south end of the nave. A small apse extends to the north with a vestry to the west and a store with a corrugated iron roof to the east.