The gray gibbon moves quickly with long leaps and swings. They are able to cover 3 meters in a single swing and around 850 meters per day. Grey gibbons walk upright with hands over head for balance when walking on the ground, although they do not cover long distances in this fashion. The gray gibbon is not a good swimmer and avoids open water. Gray gibbons are usually seen in groups of 3 or 4.
Solitary individuals are also common.
These individuals are adults who have been forced to leave the family and have not yet established their own territory. Hylobates muelleri is very territorial. About 75 percent of the home range, average size 34.2 ha., is defended. Defense involves regular morning songs and calling at and chasing intruders. Gray gibbins rarely resort to physical violence when defending territory.