The occurrence of the rays belonging to the genera Mobula (known collectively as the ‘devil rays’) and Manta is poorly documented in the eastern tropical Atlantic. Between August 2004 and September 2005, a total of 28 mobulid ray observations were recorded from geophysical survey vessels operating in the waters between Gabon and Angola. Water depth at the location of the sightings varied from 30 to 4000 m, reflecting an occurrence in both neritic and oceanic habitat. While most animals were unidentified to species level, photographs taken during two sightings facilitated the identification of two separate species/species groups of Mobula. The first individual, photographed at the surface in deep water offshore of northern Angola, was identified as belonging to the M. mobular/M. japanica species group, comprising two species that are very similar in appearance and which future evidence may reveal to represent a single species. The second animal, photographed off Pointe Noire in the Republic of the Congo, was identified as a bentfin devil ray (M. thurstoni). The previously documented southernmost records of these species in the eastern tropical Atlantic were in the Mediterranean Sea (M. mobular), Côte d'Ivoire (M. japanica) and Senegal (M. thurstoni). These observations therefore extend the known distribution ranges into the south-east Atlantic Ocean.