Sulfur　hexafluoride　(SF6)　gas　has　a　quite　high　global　warming　potential　and　hence　it　is　required　that　applying　any　substitute　for　SF6　gas.　Much　interest　in　fluorine-containing　compounds　appears　due　to　their　widespread　use　as　gaseous　candidate　of　SF6　in　fault　current　interruption　process　considering　its　relatively　high　performance　of　dielectric　insulation　and　arc　quenching.　The　critical　reduced　electric　field　strengths　of　hot　CF4　gas　corresponding　to　the　dielectric　recovery　phase　of　a　high　voltage　circuit　breaker　are　calculated　in　the　temperature　range　from　300　to　3500　K.　The　equilibrium　compositions　of　hot　CF4　gas　at　various　pressures　were　determined　based　on　Gibbs　free　energy　minimization.　Additionally,　adopting　full　sets　of　improved　cross　sections,　the　critical　reduced　electric　field　strength　of　this　derived　composition　was　obtained　by　a　balancing　electron　generation　and　loss　modeled　by　the　interactions　between　electrons　and　the　dissociated　species　of　hot　gas　evaluated　by　the　electron　energy　distribution　function　(EEDF)　derived　from　the　Boltzmann　transport　equation.　In　order　to　confirm　the　validity　of　the　present　calculation,　the　predicted　result　for　hot　CF4　gas　was　compared　with　experimental　results　and　previous　calculations　and　there　exists　a　generally　good　agreement.　We　have　presented　that　the　dielectric　strength　of　hot　CF4　gas　experiences　a　fast　reduction　as　the　continuous　dissociation　occurs　with　increasing　temperature.　Comparison　with　dielectric　properties　of　hot　SF6,　regardless　of　reduced　dielectric　properties　in　the　low　temperature　range,　replacing　SF6　with　CF4　brings　an　increase　of　the　critical　reduced　electric　field　strength　for　temperatures　above　2200　K,　indicating　possible　theoretical　verification　of　the　practical　applications　that　CF4　is　an　admixture　to　SF6　gas　as　the　arc　extinguishing　and　insulation　medium　in　high　voltage　circuit　breakers.