In　this　paper,　we　propose　an　application-driven　ALU　design　methodology　to　achieve　high　level　of　power　efficiency　for　modern　microprocessors.　We　introduce　a　PN　selection　algorithm　(PNSA)　which　enables　designers　to　select　power　efficient　dynamic　modules　for　different　applications,　based　on　the　detailed　analysis　of　dynamic　circuits.　Experimental　results　on　ISCAS85　and　74X-Series　benchmark　circuits　show　that　the　power　consumption　of　8-bit　ALU　based　on　this　approach　can　be　reduced　by　54%-60%　for　different　frequency　levels　as　compared　to　the　conventional　dynamic　ALU　design,　demonstrating　the　effectiveness　of　the　proposed　method　on　application-driven　custom　ALU　design.　©　2013　IEEE.