This paper presents some preliminary experimental measurements collected during flow boiling heat transfer of low global warming potential refrigerant R1234yf in an asymmetrically heated rectangular plain channel. The asymmetrical heating is the common boundary condition that occurs in many different applications, for instance, in almost all the electronic devices, which are now pushing the cooling demands to more and more greater requirements. From this standpoint, the analysis of the flow boiling heat transfer of efficient and eco-friendly refrigerants can open new frontiers to the electronic thermal management. The experimental measurements were carried out at the Department of Industrial Engineering of the University of Padova by imposing two different heat fluxes, 50 and 100 kW m(-2), at a constant saturation temperature of 30 degrees C; the refrigerant mass velocity was varied between 50 and 200 kg m(-2) s(-1), while the vapor quality varied from 0.2 to 0.95. The developed measuring technique permits to estimate the flow boiling heat transfer coefficient and the critical value of vapor quality at the onset of the dryout.