Recent studies using HREM techniques are yielding new insight into the nature of the layered transition metal sulfide (LTMS) catalytic materials. While the insight being generated is still at an early stage, HREM techniques are showing promise in solving complex problems in this field which have been studied for many years. HREM techniques are beginning to elucidate the structure of the catalytically active ’edge’ sites and to reveal the atomic structure of these edge terminations. HREM is also generating new insight into the problem of disorder in the layered TMS which has hindered understanding of these systems. Finally, HREM is yielding an insight into the very complex ’promotion’ problem. Evidence is presented that the older idea of pseudo-intercalation resulting in charge transfer and thus promotion may be correct.