A process includes the following steps: a) converting a solid material containing hemicellulose, cellulose and lignin, by: (i) hydrolyzing at least part of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution, yielding a remaining solid material and a hydrochloric acid-containing, aqueous, first hydrolysate product solution; (ii) hydrolyzing at least part of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution, yielding a residue and a hydrochloric acid-containing, aqueous, second hydrolysate product solution; (b) forwarding to step (c) a, hydrochloric acid-containing, aqueous intermediate product solution comprising: a part of or the whole of the hydrochloric acid-containing, aqueous first and/or second hydrolysate product solution of step (a); and (c) heating at least part of the hydrochloric acid-containing, aqueous intermediate product solution to yield a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent.