Abstract: The present invention relates to a method and a facility for conversion of organic waste into biogas, i.e. a methane containing gas, with an improved efficiency and economy. The method comprises three consecutive steps of: i) digestion of the organic waste in a first reactor; ii) hydrolysis of the digested organic waste in an anaerobic hydrolysis tank; and iii) digestion of the hydrolyzed organic waste in a second reactor; wherein evolved gases are removed from the anaerobic hydrolysis tank.