Chaotical dynamics is studied in different Friedmann-Robertson-Walker cosmo
logical models with a scalar (inflaton) field and hydrodynamical matter. Th
e topological entropy is calculated for some particular cases. The suggeste
d scheme can be easily generalized for a wide class of models. Different me
thods of calculating the topological entropy are compared. [S0556-2821(99)0
4710-4].