Preparation of chitosan from obster shells by Hackman method and modified Hackman method was compared with respect to their physico-chemical properties, molecular weight, degree of deacetylation, polydispersity and crystallinity. In modified method maximum yield (78%) of chitosan with almost 91% degree of deacetylation determined first derivative UV spectra was achieved. Molecular size distribution as well as average size of chitosan produced by Hackman method was higher (PI 1.205, particle size 1448.6 nm) and of M-wt 10 x 10(5) when compared to chitosan produced by modified Hackman method (PI 0.8832, particle size 95.3 nm) of M-wt 3.98 x 10(5). X-ray powdered diffraction showed that chitosan prepared by Hackman method was found to be more crystalline. Bragg refractions 13.3degrees2theta (d = 6.66Angstrom) and 19.7degrees2theta (d = 4.51 Angstrom), respectively than chitosan produced by modified method, Bragg refraction 13.6degrees2theta (d = 6.51Angstrom). This method provides product in less time and is economical.