A process for the stabilisation of esters of (meth)acrylic acid as a pure substance or as a component within a mixture that does not contain a Bronsted acid having a Bronsted acid strength greater than that of acrylic acid is claimed by addition of a p-phenylene diamine containing polymerisation inhibitor as a pure substance or mixture of inhibitors that contains (A) a nitroxyl radical and/or an organic compound containing a nitroso group and (B) a p-phenylene diamine.
