The aim of this work is to study the concentration, temperature and pH dependences on retention for phenol and malonic acid single solutions and their mixtures. Crossflow filtration experiments were performed to measure transport of these organic compounds across a commercially available thin-film composite nanofiltration membrane (NF-90) in the temperature range 20-41 degrees C. The influence of the feed solution pH on the rejection of phenol was verified as well. In addition, the contribution of the membrane-solute interactions on solute retention has been established.