Biomass gasification is a highly efficient conversion process that offers the possibility to convert various feedstocks to a wide variety of products. Besides fuel properties, gasifier design and operation, the gas cleaning is a key issue in the process chain. In general, the raw product gas of biomass gasification contains a range of minor species and contaminants, including particles, tar, alkali metals, chlorine, nitrogen compounds and sulphur compounds. This paper reviews the recent developments on product gas cleaning technologies for these species and summarizes the findings of the collaborative research project “Mop fan and electrofilter: an innovative approach for cleaning product gases from biomass gasification” which was recently carried out by University of Nottingham, UK (UoN), Berlin Institute of Technology, Germany (TUB), BETH Filtration GmbH and ERK Eckrohrkessel GmbH, Germany. The results of the project showed that the combination of mop fan and electrofilter (ESP) has great potential in removing fine particles, tars and chemical contaminants in the product gas.