In the present invention a method for treating algae is disclosed, which method comprises the steps of (a) providing an ionic liquid, which is a conjugate of an organic base with pKa at least 6 and an acid, (b) providing algae, (c) subjecting algae to cell lysis with the ionic liquid, whereby at least two phases are formed, including a hydrophobic phase and a hydrophilic phase, and (d) separating the hydrophobic phase containing lipids.