This article scrutinizes the Brexit party through the lens of the poststructuralist concept of populism proposed by Ernesto Laclau. The author has put forward a hypothesis whereby the Brexit party represents a new phenomenon in the political conjuncture of Europe — the ad hoc party, whereas its activity embodies the concept of disintegrational populism. The author formulates the distinctive features of the ad hoc party and disintegrational populism, which can be subsequently used in studies of European party systems. The paper argues that, unlike traditional parties, ad hoc parties which execute the logic of equivalence in their endeavors possess greater flexibility and capability to accomplish their party-constituting goals. In addition, the author suggests that disintegrational populism, alongside the logic of equivalence as the modus operandi of the party, is the most advantageous model of activity for ad hoc parties due to the peculiarities of the European political conjuncture. The research may become a theoretical contribution to the classification and taxonomization of European political parties provided the features of the European political conjuncture elucidated in the paper persist. In this regard, further research into ad hoc parties might prove extremely relevant in terms of understanding the features of modern socio-political processes in Europe.