Like other Presbytis species, the white-thighed surili is a diurnal forest dweller (6), with a diet consisting of leaves, flowers, fruit and seeds (5) (6) (9). The proportion of fruit and seeds in its diet is quite high compared with most other species in its genus (9). As in other members of the Cercopithecidae family, the white-thighed surili’s stomach is divided into a series of chambers (2) (5), allowing leafy material to be more easily broken down and toxins in the leaves to be neutralised (2).
The white-thighed surili is well adapted to living in the trees, although it may also spend time on the ground (5) (6). The home range of this species is estimated to be around 24 hectares (9), although this may vary depending on the habitat (5).
Although little information exists on the social dynamics of the white-thighed surili, it is likely that it is similar to that of closely related species. Group size of Presbytis species usually ranges from a few individuals to occasionally over 100, and each group will normally consist of one sexually mature male and numerous females (5) (6). There are also likely to be some lone males and all-male groups, and some of these males may attempt to take over a group of females or split some of the females from it (6).
Relatively little is currently known about the breeding behaviour of the white-thighed surili, but in Presbytis species in general the female gives birth to a single young at a time (6) and all adult females in a group help care for the infants (5). On reaching maturity, young males typically leave the group in which they were born (6).