  We perform a detailed study of the Globular Cluster (GC) system in the galaxy
NGC5866 based on F435W, F555W, and F625W (~ B, V, and R) HST Advanced Camera
for Surveys images.
  Adopting color, size and shape selection criteria, the final list of GC
candidates comprises 109 objects, with small estimated contamination from
background galaxies, and foreground stars.
  The color distribution of the final GC sample has a bimodal form. Adopting
color to metallicity transformations derived from the Teramo--SPoT simple
stellar population model, we estimate a metallicity [Fe/H]~ -1.5, and -0.6 dex
for the blue and red peaks, respectively. A similar result is found if the
empirical color-metallicity relations derived from Galactic GCs data are used.
  The two subpopulations show some of the features commonly observed in the GC
system of other galaxies, like a ``blue tilt'', higher central concentrations
of the red subsystem, and larger half--light radii at larger galactocentric
distances. However, we do not find evidence of a substantial difference between
the average sizes of red and blue clusters.
  Our analysis of the GC Luminosity Function indicates a V-band Turn-Over
Magnitude V$_0^{TOM}$=23.46+-0.06, or M$_{V,0}^{TOM}\sim-7.29 +- 0.10$ mag,
using the distance modulus derived from the average of SBF and the PNLF
distances. The absolute Turn-Over Magnitude obtained agrees well with
calibrations from literature. The specific frequency is measured to be $S_N=1.4
+- 0.3$, typical for galaxies of this type.
