Semiconductor ultramicroelectrodes have emerged as new tools for investigating charge transfer kinetics at semiconductor/electrolyte interfaces relevant to photoelectrochemical energy conversion. This presentation will report recent results describing the size- and solvent-dependent voltammetry obtained at unilluminated microscopic and nanoscopic Group IV and III-V semiconductor/electrolyte contacts. Three topics will be discussed. First, the experimental design for charge transfer measurements with semiconductor nanoelectrodes will be presented. This will include highlighting strategies to reduce the large capacitive contribution to the observed current and utilization of a flow cell-type design for non-aqueous electrochemical measurements. In addition, the method to extract heterogeneous rate constants and diode-quality factors directly from the carrier concentration-dependent voltammetric response will be reviewed. Next, a description of the size-dependent surface quality of semiconductor electrodes will be presented. Specifically, an examination of the diode quality factors at n-Si UMEs ranging from 10 um to 100 nm radius will be described. This will include discussion of the possibility for creating nominally defect-free semiconductor/electrolyte interfaces. Finally, charge transfer measurements at microscopic n-GaP/fullerene contacts will be demonstrated. Rate constants and diode quality factors of each observed redox transition will be presented, including solvent dependence on the wave position and diode quality factor. The implications of these results to verification of fundamental charge transfer theories will be detailed.