Novel off-centered coaxial carbon nanotubes have been fabricated by coalescing adjacent double-walled carbon nanotubes (DWNTs) using high temperature heat treatments. The eccentric nanotubes possess wide interlayer spacing, and arise by the merge of two narrow diameter (inner) tubes contained inside a large diameter tubes (also known as bi-cables). We propose a complete description of the coalescence process including the merge of two DVVNTs, followed by the formation of bi-cables and the creation of off-centered DWNTs. We also performed molecular dynamics calculations that are in agreement with the experimental observations. (c) 2006 Published by Elsevier B.V.