Chemical transformations of lignocellulosic substrates to valuable platform chemicals are challenging as lignin and cellulose have high thermal and chemical stabilities. However, certain ionic liquids are able to dissolve and deconstruct biomass and, in the presence of catalysts, convert the dissolved/deconstructed species into useful platform chemicals. Herein, we provide a concise overview of the role of ionic liquids in biomass processing. Using 5-hydroxymethylfurfural as an example of a renewable building block, available from cellulose, we show how ionic liquids can facilitate its production.