Kalophrynus baluensis is only known from the primary highland rainforests at Gunung Kinabalu, but may also occur in neighboring highlands at similar elevations (1.500 m asl).
It is a stocky, short-legged frog that is usually encountered on the forest floor, where it is perfectly camouflaged with its brown coloration in the leaf litter layer.
The call is a single note, a high pitched whistle, with long breaks between notes. Pitch and intervalls, as well as camouflage make it very difficult to locate the calling males.
According to Inger & Stuebing (2005), females reach 39 mm in snout-vent length, males remain slightly smaller.
The reproductive strategy of this species is unknown. We heard males at some distance from the water and it may be speculated whether the species breeds in phytothelmes.
This frogs has an interesting defense against predators: when molested it secretes large amounts of sticky, white slime (we did not test, but assume that the slime is not only sticky but also irritating or even toxic.