The purpose of this paper is to discuss the role of multiwalled carbon nanotube in the swelling of polyacrylamide–multiwalled carbon nanotube composites. Swelling experiments were performed in water at various temperatures by real-time monitoring of the decrease in pyranine (Py) and emission light intensity (I _em). The Stern–Volmer equation is modified for low-quenching efficiencies to interpret the behavior of pyranine intensity during the swelling of polyacrylamide–multiwalled carbon nanotube composites. The Li–Tanaka equation was used to determine the swelling time constants, , and cooperative diffusion coefficients, D, from fluorescence intensity, weight, and volume variations of the composite at various temperatures. It was observed that when decreased, naturally D increased by increasing temperatures.