Magneli phase titanium sub-oxides were identified (via X-ray diffraction) in the 1950s as a distinct series of electrically conducting compounds having the general formula TinO2n-1 where 3 < n < 10. Early research on the characterisation of materials based on TinO2n-1 has been well documented. This concise review, which is illustrated by data from the literature and our own laboratory, concerns more recent research on Magneli phase titanium oxide materials. A brief overview of chemical and physical properties is followed by the applications of electrode materials based on these titanium oxides. Energy conversion technologies (particularly batteries and fuel cells) are shown to be a continued area of research that particularly suits the relatively high electrical conductivity and chemical stability inherent in these materials. (C) 2010 Elsevier Ltd. All rights reserved.