This volume of the Modern Aspects of Electrochemistry series con- tains six chapters: four are on topics of current fundamental interest in the subject and two deal with more technological aspects of electrochemistry.

Writing such a chapter on solid metal electrodes is a challenge when, at every moment, the latest developments of surface science give rise to new possibilities and new results in this area of elec trochemistry. However, an attempt will be made to give an "up-to- date snapshot" of the state of affairs for the double layer at single- crystal electrodes of metals which are not of the transition series.

Already in this Modem Aspects of Electrochemistry series the theory and status of data for electrochemical double layers (dl) were detailed,'"3 but the sections devoted to results obtained with solid electrodes and their discussion were brief. Some aspects of the dl on polycrystalline metals, such as the potential of zero charge (pzc), were described.4 In this series a chapter was also devoted to the metal-gas interface5; certainly the comparison of this interface with that at an electrode is fruitful, although the local electric field in the latter case can be varied far more easily.