Biodiesel is an alternative diesel fuel which can be obtained from the transesterification of vegetable oils with simple alcohols. This process decreases the viscosity, density and. ash point of the raw material. The biodiesel molecular structure, consisting of linear esters, allows similar physical-chemical properties compared to mineral diesel oil. Some important properties of the oil, such as viscosity, melting point, thermal stability and cetane index can be directly related to the chemical composition of the biomass source that was used. It is therefore possible to anticipate which property values will be obtained for each biodiesel produced from a specific vegetable oil, relating them to the chemical nature of the starting vegetable oil. The objective of this study is to evaluate the properties of biodiesel oils obtained from different biomass sources (castor, soybean, cotton, and canola) and their binary blends prepared in concentration ranges between 20 and 80% vol. Each sample was analyzed for viscosity, specific gravity and iodine index. The proper formulation to meet the European specifications for biodiesel (DIN-14214) using those sources of biomass is presented and discussed. (C) 2008 Elsevier Ltd. All rights reserved.