Because of the industrial importance of C3H8 and because C3H8 hydrate is a reference material for other sII hydrates, the C3H8 hydrate dissociation conditions were independently measured using the phase boundary dissociation and isochoric methods for T = 273.63-278.75 K and p = 0.1887-18.2622 MPa. Along the liquid water Lw-H-C3H8(g) phase boundary, two different purities of 99.5 and 99.999 mol % C3H8 were studied. Data have been used to optimize two semiempirical correlations for rapid calculation of the phase dissociation conditions for p < 20 MPa. For a more rigorous model, the highest purity data have been fit using the van der Waals and Platteuw model and reference quality reduced Helmholtz equations-of-state(EOSs) for the hydrate phase and fluid phases, respectively. The optimized thermodynamic-based model agrees with the experimental data to within the estimated uncertainty of delta T = +/- 0.1 K. The results were also compared to the highly variant literature data for the Lw-H-C3H8(l) phase boundary, where the deviations, can be attributed to measurement difficulties when a hydrate is less dense than the liquid hydrate former in the liquid region.