We study four-dimensional N = 4 gauged supergravity coupled to six vector multiplets with semisimple gauge groups SO(4) × SO(4), SO(3, 1) × SO(3, 1) and SO(4) × SO(3, 1). All of these gauge groups are dyonically embedded in the global symmetry group SO(6, 6) via its maximal subgroup SO(3, 3)×SO(3, 3). For SO(4)×SO(4) gauge group, there are four N = 4 supersymmetric Ad S 4 vacua with SO (4)
×SO(4), SO(4)×SO(3), SO(3)×SO(4)and SO(3) × SO(3) symmetries, respectively. These Ad S 4 vacua correspond to N = 4 SCFTs in three dimensions with SO(4) R-symmetry and different flavor symmetries. We explicitly compute the full scalar mass spectra at all these vacua. Holographic RG flows interpolating between these conformal fixed points are also given. The solutions describe supersymmetric deformations of N = 4 SCFTs by relevant operators of dimensions = 1, 2. A number of these solutions can be found analytically although some of them can only be obtained numerically. These results provide a rich and novel class of N = 4 fixed points in threedimensional Chern-Simons-Matter theories and possible RG flows between them in the framework of N = 4 gauged supergravity in four dimensions. Similar studies are carried out for non-compact gauge groups, but the SO(4) × SO(4) gauge group exhibits a much richer structure.