A method of upgrading the properties of bio-oil with bio-diesel has been taken in this article. Firstly, the unpopular pyrolytic lignin fraction is extracted from bio-oil using ether, the rest ether-soluble fraction of bio-oil, named ES is mixed with bio-diesel according to emulsification. The optimal conditions for obtaining a stable ES/bio-diesel mixture are with octanol surfactant dosage of 3% by volume; initial ES to bio-diesel ratio of 4:6 by volume; stirring intensity of 1200?rpm; mixing time of 15?min and mixing temperature at 30 degrees C. Additionally, selected fuel properties such as viscosity, water content and acid number are measured for characterising the ES/bio-diesel mixture. Thermogravimetric analysis (TGA) has been used to further evaluate the thermal properties. Data from the TGA and Fourier transform infrared spectroscopy (FTIR) analyses confirm the presence or absence of certain group of chemical compounds in the mixture. Proton and carbon atoms assignments are further confirmed by 1H NMR (nuclear magnetic resonance) and 13C NMR analysis, respectively. (c) 2011 Canadian Society for Chemical Engineering