Nonwoven fibrous media with nanofibers havesignificant filtration applications in automotive,chemical, transportation, power generation andpharmaceutical/biological industries. Nanofibers havehigher capture efficiencies in comparison tomicrofibers in the submicron particle size range of100 - 500 nm because of smaller fiber diameter andincreased surface area of the fibers. Nanofibers arein the slip flow regime as a consequence of whichsteep increase in pressure drop is considerablyreduced due to slip effect. The economic benefits ofusing nanofiber filter media are improved filterperformance and compact filters.Electrospinning process was used to fabricate polymerand ceramic nanofibers. The electrospun polymernanofibers were added to the nonwoven fibrous mediato improve filter performance for air filtration.This improved filter performance was in consistentwith numerical modeling. This book describes theexperimental and modeling results of particle loadingon fibrous media and application of ceramicnanofibers for hot gas filtration applications.