Studying the transport (resistivity (0.4<T<150K), Seebeck coefficient
(4<T<150K), thermal conductivity (4<T<150K)), thermal expansion (0.7<T
<10K), heat capacity (0.6<T<30K) and magnetic suscuptibility (2<T<40K)
of Tb2Mo3Si4 samples with different annealing conditions we found tha
t in this superconductor (T(c) up to 1.2K) a complex magnetic structur
e exists in the normal state, characterized by antiferromagnetic trans
itions at 2.3K and 19K.