Carboxymethylchitin was prepared at different reaction temperatures and from alkali chitin with different concentrations of alkali. Properties of the product were studied. Alkali chitin were prepared using freshly prepared sodium hydroxide of 45, 50, 55, 60 and 65% (w/w) concentration and carboxymethylated using monochloroacetic acid at controlled (35-40 degrees C) and uncontrolled (30-80 degrees C) temperature conditions. Molecular weight, viscosity, degree of deacetylation, etc. of the resultant product, i.e. carboxyrnethylchitin were determined. It was found that the reaction temperature has a profound influence on the property of the product than alkali concentration. A hygroscopic and completely water-soluble product was formed. Optimum conditions for the production of carboxymethylchitin were found to be 60% NaOH concentration and at 35-40 degrees C reaction temperature. At these conditions, it was obtained with a molecular weight of 4.11 x 10(6) Da, viscosity 1926 cP and degree of deacetylation 45.02%. (c) 2005 Elsevier Ltd. All rights reserved.