The needs of environmental conservation and speed development in construction industry today have forced the search for better technologies in structural roof truss construction. Cold-formed section is a better choice for roof truss system in sustainable design with several advantages e.g. reduce cutting down of trees, speedy in construction, stronger, lighter and flexible in erection. However the stability issues occurred when wide-span roof truss is implemented with thin-walled cold-formed steel member. A full scale testing for a 25 meter wide-span roof truss system was carried out at Universiti Teknologi Malaysia to study the structural performance. The overall span of the truss is 25m in length with the height of 4.7m and the width of 1.2 m, built up by cold-formed steel channel sections of 150 mm and 74 mm in depth. Uniform loads were placed on the top and bottom chords of the truss using cement bags. The roof truss deformed at a total load of 63.77 kN or 52.7% of the designed load. Failure modes of the truss system were being observed and discussed for further improvement of the truss design.