A method has been developed for studying electrochemzal kinetic parameters of substances in powdered or dispersed form. The method is based on the frequency dependence of the ar-impedance of the powder dispersed in a suitable electrolyte. This communication presents an introductory study of p-manganese dioxide. The material was chosen in particular because of its practical importance to the dry battery industry and the numerous number of studies on its properties. The requirements to be met m investigations of the elcctro-chemical properties of this material are discussed, and a number of the methods hitherto employed for these studies are critically reviewed and compared with the techniques used in this work. The emphasis is placed on the application of ac-impedance techniques. Based on our experimental results for a typicA battery-active manganese dioxide an electrical equivalent network for the dispersion is developed. It is shown that in this case information about the interfacial impedancePreflecting diffuswn in the sohd phase --and the electronic resistance can be extracted from impedance data. The agreement between the results obtained in this way and hy other methods is not considered satisfactory. The method used in this work has principal advantages, but the results obtained depend on the correctness of several assumptions. Thcrcfore it is concluded that a broader range of cxpcriments and a rcfincment of the electrical network used 1s needed. Such invest&wtions are in progress and wkll be reported in a subsequent