  The physical properties of CsNi$_{2}$Se$_{2}$ were characterized by
electrical resistivity, magnetization and specific heat measurements. We found
that the stoichiometric CsNi$_{2}$Se$_{2}$ compound is a superconductor with a
transition temperature \textit{T$_{c}$}=2.7K. A large Sommerfeld coefficient
$\gamma$$_{n}$ ($\sim$77.90 mJ/mol$\cdot$K$^{-2}$), was obtained from the
normal state electronic specific heat. However, the Kadowaki-Woods ratio of
CsNi$_{2}$Se$_{2}$ was estimated to be about 0.041$\times$10$^{-5}$
$\mu\Omega$$\cdot$cm(mol$\cdot$K/mJ)$^{2}$, indicating the absence of strong
electron-electron correlations in this compound. In the superconducting state,
we found that the zero-field electronic specific heat data, $C_{es}(T)$ (0.5K
$\leq$ T $<$ 2.6K), can be well fitted with a two-gap BCS model. The comparison
with the results of the density functional theory (DFT) calculations suggested
that the large $\gamma$$_{n}$ in the nickel-selenide superconductors may be
related to the large Density of States (DOS) at the fermi surface.
