The electronic structure of multiwalled carbon nanotubes (CNTs) has been investigated, depending on the growth temperature, using synchrotron X-ray photoelectron spectroscopy (XPS) and field emission measurements. The vertically aligned CNTs are grown via pyrolysis of ferrocene and acetylene in a broad temperature range 600-1000 degrees C. The CNTs have a cylindrical structure with a uniform diameter of 20 run. As growth temperature increases, due to an improved crystallinity of the graphitic sheets, the width of the XPS C Is peak becomes narrower and the intensity of the valence band increases. Field emission from the as-grown CNTs exhibits a large enhancement of current density with growth temperature, strongly correlated with the electronic Structure revealed by XPS.