PURPOSE: A molding compound with excellent strength, useful as an encapsulating material, a dialysis material, an ion-exchange material, etc., which is obtained by the acylation or acid treatment of part of a crosslinked chitin derivative.

CONSTITUTION: One or a mixture of at least two, of ionic crosslinked chitin derivatives of formula IV or V, having a main structure of formula I or II [wherein R1 is H, CnH2n+1, (CH2)nOH or CO(CH2)n-1CH3; R2 is H, CnH2n+1, (CH2)nOH, formu la III, (CH2)n or COOM, m is 1W20; M is H or an alkali (or alkaline earth) mettal], in which the 3 and 6' positions, or the 3, N and 6' positions are crosslinked to a degree of crosslinking of 0.01W0.3, is acylated by reaction with an organic acid (anhydride) such as acetic acid (anhydride) or propionic acid (anhydride) at 5W 80°C, to obtain a chitin molding compound.