The magnetic properties of the simple perovskite-like structured BaTb(1-x)InxO(3-x/2+y/2)H-y, 0 less than or equal to x less than or equal to 0.47, further called BTI, has been investigated in the dry state (y = 0) and in the completely wet state (y = x). The Neel temperature, being T-N = 33.5 K for the pure BaTbO3, is found to be reduced as a function of the indium concentration, x, and is 16 K for x = 0.4. Although BTI in the dry state, which has the cubic structure, seems to be a pure antiferromagnet (AF), additionally a small ferromagnetic (F) component of about 0.015 mu(B)/Tb ion is observed for BaTbO3 and the wet BTI samples. Apparently this F contribution is related to the non-cubic environment of the Tb4+ ions in the latter compounds. (C) 1998 Elsevier Science B.V. All rights reserved.