Potassium salts are widely distributed both on the land and in the sea. Potassium ions play important roles in diverse cellular functions in all living organisms including plants, animals, and humans. Potassium-bearing minerals and salts are widely used as fertilizers and raw materials in agriculture and the chemical industries. In addition, potassium-bearing bases including KOH and KOtBu have been frequently used as bases or catalysts in C–C bond formations in organic synthesis. Significant advances have been made in the past decades in the catalytic application of potassium compounds in the synthesis of various organic molecules. The present chapter provides an overview on recent developments in the catalytic use of potassium species in organic synthesis. According to the reaction types, the chapter is divided into seven sections including: alkene isomerization; hydroamination; hydrophosphination; hydrosilylation; hydrogenation; C–H bond alkylation; radical chemistry. These reactions mediated by potassium-containing bases rely on the “base” character of these species rather than the intrinsic features of “potassium”; these potassium catalysts are considered here as “organometallic compounds”. This chapter focuses on reactions in which potassium catalysts were shown to display much better activity than their sodium and lithium analogues.