Abstract Neocamarosporium aquaticum, collected from a drift dead stem of a halophyte at the Kench Nature Reserve, Hayling Island, UK, is described as a new species in the family Neocamarosporiaceae, Dothideomycetes. Multi-locus analyses based on LSU, SSU, ITS rDNA, and EF1-α placed the new fungus as a distinct species in the genus Neocamarosporium, a sister to Neocamarosporium aesturinum isolated from seawater. The new species is characterized by the asexual morph with pycnidial conidiomata, doliiform, enteroblastic, annellidic conidiogenous cells, and conidia that are initially hyaline, aseptate, with longitudinal and transverse septa when matured, muriform, and turning brown to dark brown on maturity. Neocamarosporium aquaticum and Ne. aesturinum differ in the colour of the conidia, degree of septation, and conidial measurements.