An interdigitated microelectrode (IME) coated with a glassy polymer of V2O5 by a sol-gel process is demonstrated to serve as a solid electrolyte for voltammetric studies in the absence of a contacting solution phase. The oxidation of iron(II) 1,10-phenanthroline immobilized therein occurs at the same potential as in solution-phase experiments at a Pt working electrode; however, the current limiting process in the solid-state system is dependent on the time scale of the experiment. Cyclic voltammetry at scan rates of 0.1 to 1.0 V s(-1) yields currents limited by planar diffusion, but below 3 mV s(-1) the peak currents are independent of scan rate. This steady-state behavior in the coated IME is indicative of current limitation by semi-cylindrical diffusion to the 10 mu m x 5 mm Pt surfaces at slow scan rates; potential step chronoamperometry verifies this interpretation. When one set of Pt fingers in the IME is a quasi-reference and the other set is modified with a polymeric ruthenium oxide catalyst, the presence of ammonia in the surrounding gas phase causes an anodic process. Indirect evidence that this process is the electrocatalytic oxidation of ammonia is presented. This anodic behavior is not observed when the voltammetry is performed in a conventional solution cell under otherwise-identical conditions.