Brønsted acid catalysis has emerged as a new class of catalysis in modern organic synthesis. However, in order to make the utility of the Brønsted acid catalysis as broad as the well-developed Lewis acid catalysis, it is desirable to develop Brønsted acids demonstrating both high reactivities and selectivities. In this feature article, we will present our achievement in the design and development of strong Brønsted acids and their application to organic reactions. Furthermore, we will describe the Tf(2)NH-catalyzed Mukaiyama aldol reaction of super silyl enol ethers. We also will highlight the differences in reactivity and chemo- and stereo-selectivity between Brønsted and Lewis acid catalysis.