Double-walled carbon nanotubes (DWCNTs) were synthesized by using thermal chemical vapor deposition on MgO-supported FeMo catalysts, in the temperature range 800-1000 degrees C Outer diameters were 1.5-2 nm at all growth temperatures. As growth temperature was increased, C1s peaks of X-ray photoelectron spectroscopy became broader and valence band intensity increased due to stronger van der Waals interaction between DWCNTs induced by higher crystallinities. Field emission from the as-grown DWCNTs exhibited a large current density enhancement with increasing growth temperature. (c) 2006 Elsevier B.V. All rights reserved.