We present measurements of binary homogeneous nucleation of sulfuric acid and water vapors at 298 K at two different relative humidities (38.2% and 52.3%), H2SO4 vapor concentrations ranging from about 1.10(10) to 3.10(10) molecules/cc. The experimental setup consisted of a turbulent mixing unit combined with a flow chamber where the nucleation took place. Particular attention was paid to the generation of sulfuric acid vapor. The measured nucleation rates vary between about 2 and 3000 cm(-3) s(-1). The results are compared with other measurements found in the literature. Our experimental rates are in agreement with predictions of the revised classical nucleation theory incorporating the hydration effect.