A metal gate structure with a channel material and methods of manufacture such structure is provided. The method includes forming dummy gate structures on a substrate. The method further includes forming sidewall structures on sidewalls of the dummy gate structures. The method further includes removing the dummy gate structures to form a first trench and a second trench, defined by the sidewall structures. The method further includes forming a channel material on the substrate in the first trench and in the second trench. The method further includes removing the channel material from the second trench while the first trench is masked. The method further includes filling remaining portions of the first trench and the second trench with gate material.