Electrochemistry provides chemistry of nanomaterials with a simple and efficient method of generation of atomic layers of various elements. The underpotential deposition, upd, is the cathodic deposition of adsorbed atom, adatom, above the reversible potential of the corresponding equilibrium phase cathodic deposition, or anodic deposition below the reversible potential of the corresponding anodic reaction. The upd terminates upon formation of a monolayer, as the potential shift which allows the surface limited reaction to proceed at its characteristic potential apart of the bulk phase deposition is due to adatom-substrate interaction. The upd potential shift is governed by work function differences of the substrate and deposited metal in the upd of metal on metal (a less noble metal is deposited underpotentially onto a more noble metal), but factors other than work function differences control the upd potential shift in systems with covalent adatom-substrate bonding [1].  Upd of metal adatoms on chalcogen and semiconductor chalcogenide substrates, as well as chalcogen upd on metal are of special interest for energy applications (thermoelectric, solar energy conversion). The upd acts as a precise nano-batcher which introduces very small amount of material into solid state reactions controlled on the atomic scale, e.g. upd of lead on tellurium nanoparticles supported by bismuth telluride provides a controlled transformation of Te nanoparticle into PbTe in multiple cycles of the electrode potential scan. Lead adlayer, Pbad, cathodic deposition and anodic oxidation on Bi2Te3-Te nanoheterostructure, proceeds reversibly on Bi2Te3 component, while a small fraction of those Pbad which are formed on tellurium (within 10% of adlayer in each cycle) interacts chemically with Te. The growing PbTe nuclei, similarly to Bi2Te3, show affinity to acquire reversibly Pbad at characteristic potential of the upd, which provides in situ monitoring of the electrochemically stimulated nanochemical reaction by electrochemical methods. A set of methods has been developed for detailed characterization of the variable electrochemical interfaces with adlayers by their electrochemical responses in direct and alternating currents. Upd potential shifts on CdS and CdSe quantum dots (QD) were found to be dependent on QD size, which provided the QD size determination from electrochemical measurements [2]. Selective upd of cadmium on CdSe nanoparticles supported by wide bandgap oxides (TiO2, ZnO) has provided the efficient method of real surface area measurement of the chalcogenide sensitizer of photoelectrochemical reactions on the wide bandgap oxides [3]. Bi atomic layers were electrochemically introduced onto and into Bi2Te3 crystals resulting in formation of (Bi2)m(Bi2Te3)n superlattices with specific electronic properties which were characterized in situ by potentiodynamic electrochemical impedance spectroscopy.