The present study concerns corrosion of aluminium and copper in ultra low sulphur diesel fuel and its blends with rapeseed methyl ester. Tests were carried out at wide ranging contents of rapeseed methyl ester (0%, 50%, 75% and 100%) at 80 °C for 600 h. At the end of the immersion test a comparison was performed by weight loss corrosion rate measurement and by analysis of damages of metal surfaces. Analysis of fuels was performed by using total acid number measurement and by gas chromatography-mass spectrometry to investigate the acid concentration and change of fuel composition respectively. Damages afflicted on metal surfaces were examined by scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS). Results showed that increasing the biodiesel content enhanced the corrosiveness of blend to both metals; this was confirmed by analyses of fuel properties and damage on metal surfaces exposed to fuels. Also it was found that copper was more vulnerable to attack compared with aluminium for all blends.