We report our investigations done on TiMn1.5 intermetallics in relation to hydrogen storage behaviour. TiMn1.5 is known to exhibit the clear plateau in the series TiMn2-x (x = 0-1.25). This communication describes the synthesis of TiMn1.5 by using r.f. induction furnace and characterization by employing, X-ray diffractometry, transmission electron microscopy and Sievert's apparatus for hydrogen desorption characteristics. The correlation between the microstructural characteristics and the hydrogenation behaviour for TiMn1.5 is discussed. The clarity of the plateau pressure is supported by the occurrence of ordered superstructure in the partially hydrogenated sample. The superstructure has the periodicity a(mod) = (8/root3)a(parent). Electron micrographs of the hydrogenated samples at successive stages showed dendritic rupturing of the as-synthesized TiMn1.5. A model has been proposed to explain the stability and hydrogenation behaviour of TiMn1.5 with a modified structure in which Ti atoms substitute for Mn vacancy and at the same time softens the void to accommodate hydrogen.