A flow-mixing calorimeter has been used to measure the excess molar enthalpyH m E of (cyclohexane+tetrachloromethane)(g) and (benzene+tetrachloromethane)(g) at standard atmospheric pressure over the temperature range 353.2 K to 423.2 K. The non-ideality of the cyclohexane, benzene, and tetrachloromethane was fitted using the Kihara potential. Cross-terms were calculated using the equation ε 12 =(1−k 12 )(ε 11 ε 22 ) 1/2 , and to fit the measurements on (cyclohexane+tetrachloromethane)(g) the value of (1−k 12 ) was 1.0005, while to fit the measurements on (benzene+tetrachloromethane)(g) the value of (1−k 12 ) was 0.996. This implies that the gas phase interaction between benzene and tetrachloromethane is slightly weaker than the interaction between cyclohexane and tetrachloromethane. In marked contrast to liquid phaseH m E measurements, no evidence of a specific interaction between benzene and tetrachloromethane was found. Second virial cross coefficients obtained from the measurements are in agreement with those obtained from (p,V,T).Measurements ofH m E on (cyclohexane+chloromethane)(g) and (benzene+chloromethane)(g) were also made. The non-ideality of chloromethane was fitted using the Storvick–Spurling potential. The (cyclohexane+chloromethane)(g) measurements are well fitted using (1−k 12 )=0.88. The (benzene+chloromethane)(g) measurements were fitted using a quasi-chemical model which, for benzene–chloromethane association, yielded a value of the equilibrium constantK 12 (298.15 K)=0.179 MPa −1 and an enthalpy of association ΔH 12 =−(7.17±2) kJ·mol −1 .