Tin phosphide (SnP0.94) particles were synthesized by thermal decomposition of tin acetate in a mixed solution of trioctylphosphine and a high-boiling solvent. Teardrop-shaped SnP0.94 particles with the size of about 500 nm were obtained by using trioctylphosphine oxide as a coordinating solvent. In the case using oleylamine as a solvent, the shape of SnP0.94 particles was not uniform. Formation mechanism of teardrop-shaped SnP0.94 was discussed. SnP0.94 particles prepared by using the trioctylphosphine oxide as a coordinating solvent were applied as an active material to all-solid-state lithium cells. The cell Li-In/80Li(2)S center dot 19P(2)S(5)center dot 1P(2)O(5)/SnP0.94 exhibited the initial discharge capacity of 1000 mAh g(-1) at a current density of 1.3 mA cm(-2). (C)2010 The Ceramic Society of Japan. All rights reserved.