This paper analyzes the uncertainties propagation of the theoretical model developed to simulate the thermal performance of PCM-air heat exchanger. Numerical results are compared with experimental results obtained with a full-scale heat exchanger prototype. In the model, the energy equation is considered in terms of enthalpy, as the governing equation can be applied at any stage, determining the temperature at each point and therefore assessing the value of the PCM thermophysical properties. Due to the uncertainties of the input variables, this analysis provides a band of uncertainty associated with the solution that is useful and more realistic when comparing the experimental and simulated results. In this sense, for most of the process, there has been observed a high degree of overlapping between the two different heat rate curves. For this type of heat exchangers, the uncertainty propagation analysis also quantifies the consequences that imply making the effort of improving the determination of a parameter or enhancing the measurement of a variable. In this study case, it is not worth to invest efforts in determining the average phase change temperature of a PCM with an uncertainty better than +/- 0.25 degrees C when the main response is the average heat rate. (C) 2011 Elsevier B.V. All rights reserved.