Weight- loss, potentiodynamic polarization and electrochemical impedance spectroscopy ( EIS) measurements were used to study the inhibition of 304 stainless steel corrosion in 1 M H2SO4 at 50degreesC by propargyltriphenylphosphonium bromide ( PgTPhPBr). The inhibiting effects of propyltriphenylphosphonium bromide ( PrTPhPBr) and propargyl alcohol ( PA) were also studied for the sake of comparison. For the investigated compounds, Tafel extrapolation in the cathodic region gave a corrosion inhibition efficiency of 98% at 1 x 10(-3) M. Adsorption of both PgTPhPBr and PA was found to follow Frumkin's isotherm while adsorption of PrTPhPBr obeys that of Temkin. In the anodic domain, PgTPhPBr acted as a good passivator. The impedance spectra recorded at the corrosion potential ( E-cor) revealed that the charge transfer process in the inhibited and uninhibited states controls corrosion of 304 stainless steel.