Direct ammonium carbonate-and ammonia-based fuel cells with an anion exchange membrane (AEM) and Pt/C catalyst have been constructed and their performance has been evaluated. Ammonium carbonate, which has never been used as a fuel, can become massively available when CO2 is captured with ammonia as a non-recyclable, single-use adsorbent. It is a solid at ambient conditions and thus as a fuel option, has the advantages of volumetric energy density, ease of transportation, and storage safety. In this paper, the oxidative activities of the Pt/C catalyst on ammonium carbonate, along with ammonia, were evaluated by means of a half-cell test. Ammonium carbonate exhibited approximately 75% of the oxidation activity of ammonia; this reduced activity was likely attributable to the existence of the carbonate. This was also observed in a single cell test: the direct ammonium carbonate fuel cell generated approximately 50% lower maximum power density than that of an ammonia-based counterpart. Although its performance is seemingly inferior, it turns out that the energy power is comparable to pure ammonia or at least in the same order of magnitude. We showed that ammonium carbonate has enough potential as a fuel in low temperature polymer fuel cells.