Required microscope conditions and the technique of photography and development procedures are described, and means of improvement suggested for high resolution, high magnification 16 mm cinematography of chemical reactions at high temperature in the electron microscope. It is shown experimentally that, even with an externally mounted camera, resolutions of 12–15 Å can be achieved in practice at reaction temperatures of 1000–1100°C and magnifications of 110 000 × on the microscope fluorescent screen. Standard 16 mm reversal film exposed at 2 frames∕ sec for 0.2 sec∕frame and f∕1.8 lens aperture are adequate but require accurately controlled development conditions. It is therefore shown quantitatively that it is possible to obtain higher resolution at shorter exposure times by photographic means than by more complicated and more costly electronic equipment. Standard electron microscope movie attachments were considered but vibration alone prohibits their use for high resolution recording. Photographic grain structure remains the major factor limiting high resolution cinematographic recording in the electron microscope. Reaction is observed between MgO and the Pd specimen support grid. A phase behaving like a liquid forms and extends over the surface, stripping the crystal via a surface mechanism, changing shape and contracting back into the main body of the phase.