  We study N=6 gauged supergravity in three dimensions with scalar manifolds
$\frac{SU(4,k)}{S(U(4)\times U(k))}$ for $k=1,2,3,4$ in great details. We
classify some admissible non-compact gauge groups which can be consistently
gauged and preserve all supersymmetries. We give the explicit form of the
embedding tensors for these gauge groups as well as study their scalar
potentials on the full scalar manifold for each value of $k=1,2,3,4$ along with
the corresponding vacua. Furthermore, the potentials for the compact gauge
groups, $SO(p)\times SO(6-p)\times SU(k)\times U(1)$ for $p=3,4,5,6$,
identified previously in the literature are partially studied on a submanifold
of the full scalar manifold. This submanifold is invariant under a certain
subgroup of the corresponding gauge group. We find a number of supersymmetric
AdS vacua in the case of compact gauge groups. We then consider holographic RG
flow solutions in the compact gauge groups $SO(6)\times SU(4)\times U(1)$ and
$SO(4)\times SO(2)\times SU(4)\times U(1)$ for the k=4 case. The solutions
involving one active scalar can be found analytically and describe operator
flows driven by a relevant operator of dimension 3/2. For non-compact gauge
groups, we find all types of vacua namely AdS, Minkowski and dS, but there is
no possibility of RG flows in the AdS/CFT sense for all gauge groups considered
here.
