Experimental total pressure measurements of propyne mixed with propane, propene, and propadiene are presented for five isotherms from 253 to 353 K. Thermodynamically consistent vapor compositions and saturated phase densities are calculated using a cubic equation of state with three isothermal pure component parameters and two binary mixture parameters. The precision vapor-liquid equilibrium cell and experimental procedure which are particularly useful for measurements involving close boiling light hydrocarbons are described, and the experimental and modeled results are presented.