This paper presents a study of heating-induced size and shape change for pre-synthesized composite nanoparticles of ∼2 nm gold cores encapsulated with alkanethiolate monolayers. The results have demonstrated an evolution in size and shape of the nanoparticles towards monodispersed larger core sizes with well-defined and highly-faceted morphologies. The evolved particles were encapsulated with the thiolate shells. The morphological and structural evolutions were characterized using TEM, XRD, UV-Vis and FTIR spectroscopy. While temperature-driven crystal growth is known for non-encapsulated particles, the evolution of the thiolate-encapsulated nanoparticles in solutions into well-defined morphologies represents an intriguing example of temperature manipulations of nanoparticle monodispersity and shape.