Abstract There are already methods for visual observation of heterogeneous reaction rates. A new method for visualizing low intensity heterogeneous reactions is presented. The method is based on a previously unknown “chemography” effect when a surface undergoing oxidation creates its own hidden image on a photoemulsion layer situated close to the surface. The image arises due to the flow of active molecules which are desorbed spontaneously by the oxidizing solid surface in the environment. The effect is observed for the oxidation of some metals and semiconductors. The run of the low intensity Si-oxidation reactions at room temperature versus environment composition has been investigated by this method. The influence of a glow discharge atmosphere on the “chemography” effect of Si was also studied. The possible use of this effect for recording molecular and ion flows was demonstrated. The authors propose to use the “chemography” effect for the investigation of kinetics of the heterogeneous reactions and heterogeneous catalysis.