Graphene, or single layered graphite, with its high crystallinity and interesting semi-metal electronic properties, has emerged as an exciting 2-D material showing great promise for the fabrication of nanoscale devices1-3. Thin, elongated strips of graphene that possess straight edges, termed graphene ribbons, gradually transform from semiconducting to semi-metals as their width increases4-7 and represent a particularly versatile variety of graphene. Several lithographic7,8, chemical9-11, and synthetic12 procedures have been reported to produce microscopic samples of graphene nanoribbons while one chemical vapor deposition process13 has successfully produced macroscopic quantities of nanoribbons at 950 °C. Here we describe a simple, high-yielding solution-based oxidative process for producing nanoribbon structures by lengthwise cutting and unraveling of multi-walled carbon nanotube (MWCNT) sidewalls. Although oxidative shortening of MWCNTs has previously been achieved14, lengthwise cutting is heretofore unreported. Uniform structures with straight edges and high water solubility are obtained. Subsequent chemical reduction of the ribbon structures from MWCNTs results in restoration of electrical conductivity.