Modification of electrodes with metal nanoparticles (NPs) is attracting intense interest because of the widespread applications of these electrodes as sensors in electroanalysis. In the present study, we have analysed the electrodeposition of gold nanoparticles (Au NPs) on a platinum electrode in the presence of polyvinylpyrrolidone using UV/Vis spectroelectrochemistry, which allows us to obtain in situ evidence on the kind of nanoparticles deposited on the electrode. Under the selected experimental conditions, it has been possible to understand the reaction pathway for the synthesis of Au NPs in a voltammetry experiment. We establish that generation of NPs of a specific size is dramatically favoured during the different oxidation and reduction processes. Experiments with and without protective agents revealed that NPs generation is favoured from the first cycle when a protective agent is present in solution
