Cloud and pour points are part of the specifications for diesel fuel oils. This work studies the dilution of a diesel with a jet fuel of very low cloud point to produce fuel blends with lower cold characteristics. It is shown that the cloud point of the blend is a highly non-linear combination of the cloud points of the original fuels and is mainly dependent on the cloud point of the heavier fluid. Using a thermodynamic model previously proposed, an accurate description of the cloud point for the fuel blends is achieved. This model also allows an estimation of the amount of solid at the pour point showing that as little as 0.5-1 wt% of solids axe enough to gel the fuel. (C) 2002 Elsevier Science Ltd. All rights reserved.