  We derive the action for a massive tensor multiplet coupled to chiral and
vector multiplets as it can appear in orientifold compactifications of type IIB
string theory.We compute the potential of the theory and show its consistency
with the corresponding Kaluza-Klein reduction of N=1 orientifold
compactifications. The potential contains an explicit mass term for the scalar
in the tensor multiplet which does not arise from eliminating an auxiliary
field. A dual action with an additional massive vector multiplet is derived at
the level of superfields.
