X-ray diffraction (XRD) and differential scanning calorimetry (DSC) are widely used to measure changes in physical and chemical states, such as phase transition, crystallization, dehydration, and decomposition, in solid substances. Rigaku Corporation’s simultaneous measurement instrument for XRD and DSC (hereafter referred to as the XRD-DSC) is configured with a general-purpose X-ray powder diffractometer and a DSC as an attachment. As an instrument capable of providing information on thermal and structural changes in a single measurement, it has won high regard in research and development involving pharmaceuticals, complexes, liquid crystals, catalysts, high polymers, and electronic materials. This paper introduces the features of the XRD-DSC and the latest data obtained using a highspeed one-dimensional X-ray detector.