Chemical size effect on structural and magnetic properties in (Ca2-2xSr2x)FeMoO6 has been examined. The compounds crystallize in the monoclinic system for 0.0less than or equal tox<0.2, the orthorhombic for 0.2less than or equal tox<0.4 and the tetragonal for 0.4less than or equal tox. The Curie temperature T-C increases with increasing x from 318 K (x = 0.0) to 393 K (x = 1.0). At 82 K, the saturation magnetization of all samples remains M(S)less than or equal to3.5mu(B)/formula unit compared to a theoretical spin-only moment 4mu(B)/formula unit for a perfectly ordered compound. This discrepancy is probably due to a slight disorder and valence-fluctuation between the Fe and Mo atoms.