An exhaustive experimental study of the critical heat flux (CHF) at flow boiling of R-134a  in a vertical tube has been recently completed. The objective of this study was to provide a consistent set of CHF data over a wide range of flow conditions including the so-called limiting critical quality region. This database will serve as a reference for future analyses. The investigated range of flow parameters in R-134a was: outlet pressure: 0.96 - 2.39 MPa (equivalent to 6-14 MPa in a water), mass flux: 210-3500 kg m^-2  s^-1 (equivalent to 300-5000 kg m^-2 s^-1 in water), and critical quality -0.1 – +1. To extend the range of critical qualities, different heated lengths (0.45-2m) and two-phase flow at inlet to the test section were used. This is the most exhaustive CHF database obtained to date in R-134a in a multi-fluid loop facility at the Mechanical Engineering Department of the University of Ottawa.