The bacterial genus Klebsiella includes the closely related species K. oxytoca and K. pneumoniae, which while part of the normal flora, are capable of causing severe disease in humans. In this report we describe the isolation, genomic and functional characterisation of the lytic bacteriophage KOX9, which is specific for K. oxytoca. KOX9 belongs to the family Drexlerviridae, and has a novel genome which shares very little homology (71.89 % identity over a query cover of only 8 %) with that of its closest related bacteriophage. KOX9, which does not apparently possess any putative depolymerase enzyme, was shown to be capable of degrading mono-biofilms of a strain of K. oxytoca which carried the polysaccharide capsule KL70 locus. This is the first report of a bacteriophage capable of breaking down a biofilm of this species.