A capacitor that is capable of exhibiting good electrical properties even under a variety of conditions is provided. More particularly, the capacitor contains a capacitor element that comprises a sintered porous anode body formed from a powder having a specific charge of about 100,000 μF*V/g or more; a dielectric that overlies the anode body; and a solid electrolyte that overlies the dielectric. The solid electrolyte contains an in situ-polymerized conductive polymer. Further, the capacitor exhibits a leakage current of about 110 microamps or less at a temperature of about 23° C. after being subjected to an applied rated voltage.