Highlights: C12H26-C13H28 system has a congruent minimum-melting solid solution and polymorphs  The minimum-freezing 17.7 mol% C13H28 blend (at -16 to -12 °C ) is a potential PCM  17.7 mol% C13H28 blend freezes with an enthalpy of 165 kJ kg -1 and no supercooling  The system has a minimum-melting trend, but has no eutectic as literature proposed  Extensive physicochemical studies needed to explain melting/freezing discrepancies AbstractIntegrating thermal storage with phase change materials (PCMs) in refrigeration and air conditioning processes enables energy performance improvements. Herein, the experimental phase diagram of the alkanes system dodecane-tridecane (C 12 H 26 -C 13 H 28 ) is evaluated to find PCMs for freezing applications. For that, the Temperature-history method was coupled with a Tammann plot analysis. The obtained C 12 H 26 -C 13 H 28 phase diagram indicated a congruent minimum-melting solid solution and polymorphs. The minimum-melting liquidus and the polymorphs identified here, agree with previous literature. However, the system does not represent a eutectic, as previously was proposed. The minimum-melting composition is here identified within 15-20 mol% C 13 H 28 compositions. The 17.7 mol% C 13 H 28 is the narrowest minimum-melting composition among those analyzed, melting and freezing between -16 to -12 °C and -17 to -15 °C, with: the enthalpies 185 kJ kg -1 and 165 kJ kg -1 ; no supercooling; and only minor hysteresis. Hence, this blend has potential as a PCM in freezing refrigeration applications.