This paper studied the KOH-catalyzed pyrolysis of rice husk (RH) and its pellet (RHP) at a high temperature (750 degrees C) for activated bio-carbons production. The mass ratio of KOH and biomass greatly impacted the pyrolysis kinetic and biochar property. The KOH catalysis (mass ratio: 1) reduced significantly the activation energy to 41 kJ/mol. During carbonization with KOH, the in-situ generated K2CO3 tailored the morphology and size of the self-template (SiO2 nanoparticles), giving rise to the chars with the open foam-like porous architectures enrich in micro-and meso-pores. Thus, the KOH activation via one-step pyrolysis could produce the micro-mesoporous carbons (e.g., RH-char 1 and RHP-char 1) with high specific surface areas and high content of oxygen-functionalities. Furthermore, the hierarchical porous carbons have high potential applications in adsorption process and electrochemical energy storage (e.g., supercapacitor) because of their unique physicochemical properties.