The vapor pressure of isobutane (R600a) was measured using a modified Burnett PvTx apparatus at temperatures from 253 to 393 K and pressures from 73 to 2833 kPa. The measurement uncertainties were estimated to be within for temperature and within for pressure. A new vapor pressure equation was developed to represent the experimental data of R600a. The present equation was also compared with available literature data. The normal boiling point and acentric factor of R600a were also determined.