Enzymatic depolymerization of chitosan (acetylation degree and average viscosimetric molecular weight (M ) of 0,85 and 310 kDa, respectively) was studied using commercial v bromelain. Decrease of the average viscosimetric polymerization degree (X ) was followed in V a buffer solution of acetic acid (0,3 M)/sodium acetate (0,2 M) at 25 oC. Under these experimental conditions it is possible to relate the instantaneous intrinsic viscosity [η ] with M v through the Mark-Houwink-Sakurada equation. Equations of Sano, which allow to compute values of intrinsic viscosity with a single measurement of relative and/or specific viscosity, was employed to obtain instantaneous values of [η ], which were also obtained for comparative purpose through an iterative process using Huggins equation. Initial velocity of depolymerization (v ) was obtained from different concentration of chitosan solutions and a o