The ultrafine composite fibers consisting of lauric acid (LA) and polyamide 6 (PA6) were prepared via the technique of electrospinning as form-stable phase change materials. The influences of carbon nanofibers (CNFs) on structural morphology, as well as the properties of thermal energy storage, thermal stability, and thermal conductivity, of electrospun LA/PA6 composite fibers were studied. FE-SEM images revealed that the morphologies of electrospun LA/PA6/CNFs composite fibers changed from cylindrical shape with smooth surface (neat PA6 nanofibers) to non-uniform and coarse structure, and the CNFs were uniformly/randomly dispersed in the composite fibers. DSC measurements indicated that the heat enthalpies of the composite fibers were lower that that of neat LA powder, and the amount of CNFs in the fibers had slightly influence on the crystallization of LA (i.e., heat enthalpies of the composite fibers); while it had no appreciable effect on the phase change temperatures. TGA results suggested that the incorporation of the CNFs increased the maximum weight loss temperature and charred residue at 700oC of the composite fibers, indicating the improved thermal stability for composite fibers. The increased thermal conductivity was also confirmed by comparison of the melting/freezing times of neat LA powder with those of composite fibers with and/or without CNFs. It was envisioned that the electrospun LA/PA6 ultrafine composite fibers would be utilized for latent heat thermal energy-storage applications because of its desired structural morphologies and thermal properties.