The hydrothermal stability of TiO2-ZrO2 nanofiltration (NF) membranes fired at 200,400, and 550 degrees C was examined at 90 degrees C for 4-100 h, followed by an evaluation of the NF performance at 25 degrees C. After hot-water treatment, the water permeability (L-p) of a membrane fired at 200 degrees C had slightly increased, while that of membranes fired at 400 and 550 degrees C had drastically decreased. Meanwhile, the values for molecular weight cut-off (MWCO) were decreased for all membranes. The L-p and MWCO changed during the initial 20 h and remained constant for as long as 100 h, confirming the stability in an aqueous solution at 90 degrees C. The permeation properties of water and neutral solutes were evaluated for temperatures that ranged from 25 to 85 degrees C. The water permeability and permeate flux increased with an increase in temperature, while the rejection of solutes decreased. Based on analysis using the Spiegler-Kedem equations, the reflection coefficient was constant irrespective of permeation temperature, while both water and solute permeability were increased with an increase in the permeation temperature, which revealed that the permeation mechanism of water and neutral solutes is an activated process. In addition, the activation energies of solute permeability were found to be higher than those of water permeability.