The inhibitive action of Hydroxylammonium sulfate ((NH3OH)2SO4) (HAS) on corrosion inhibition of carbon steel (CS) in 1M HCl was studied by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and effect of temperature. The measurements show that inhibition efficiencies increases with increasing of HAS concentrations but decreases with increasing temperatures. This reveals that inhibitive action of inhibitor was mainly due to adsorption on the carbon steel surface and blocked the active sites. The above results showed that HAS acted as a mixed-type corrosion inhibitor. The adsorption of HAS on the carbon steel surface obeyed the Langmuir adsorption isotherm. This was supported by the impedance measurements which showed a change in the charge transfer resistance and double layer capacitance indicating adsorption of HAS on the carbon steel surface. Thermodynamic parameters of studied inhibitor were calculated and discused.