Chitin and chitosan with improved characteristics were produced from shrimp shell waste preconditioned by limited decay or by treatment with 0.016 mol L-1 benzoic acid. Preconditioned shrimp shells were transparent, had a clean surface and were susceptible to demineralization and deproteinization using 0.68 mol L-1 HCl and 0.62mol L-1 NaOH, respectively. The ash and protein residues in the final chitosan were about 0.2% and 0.4%, respectively, the viscosity was up to 7000 cps, and the solubility and transparency nearly 100%. In comparison with treatment at ambient temperature (30 degrees C) without preconditioning, the chemical consumption, the duration of the treatment, ash and protein residues was reduced to 75-25%, whereas viscosity and absence of insolubles improved by a factor of 2-3. (c) 2006 Society of Chemical Industry.