Abstract This paper shows experimental results about R1234yf condensation inside a microfin tube with an inner diameter at the fin tip of 3.4 mm. R1234yf is a new environmentally friendly refrigerant, with a Global Warming Potential lower than 1, therefore it matches the new environmental laws. Experimental tests are carried out for mass velocities from 100 to 1000 kg m −2 s −1 , vapor qualities from 0.95 to 0.2, at saturation temperature of 30 °C and 40 °C. The experimental results show that heat transfer coefficient increases when both mass velocity and vapor quality increase. Frictional pressure gradient increases with mass velocity at constant vapor quality, whereas at constant mass velocity it increases with vapor quality up to a maximum, after which it slightly decreases. The experimental heat transfer coefficient and pressure drop are also compared against the values predicted by empirical correlations available in the open literature.