A simultaneous differential scanning calorimeter (DSC)-optical video microscope instrument has been developed. The instrument development included slight modifications to the sample head of a Perkin-Elmer DSC-7, along with the use of a CCD camera and magnifying lenses. The instrument permitted simultaneous following of optical and thermal events during isothermal and non-isothermal DSC experiments. The DSC curves were almost identical to those given by a standard DSC-7. The operational temperature range of the instrument is between −160 to 600°C. The capabilities of the DSC-video microscope are illustrated by examples of ice crystallization data in aqueous solutions of glycerol and dimethyl sulphoxide.