Deep VLT optical spectroscopy , HST+ACS ( GOODS ) imaging and VLA observations are used to unveil the nature of a complete sample of 47 EROs with R - K _ { s } > 5 and K _ { s } < 20 .
The spectroscopic redshift completeness is 62 % .
Morphological classification was derived for each ERO through visual inspection and surface brightness profile fitting .
Three main ERO morphological types are found : E/S0 galaxies ( \sim 30 - 37 % ) , spiral-like ( \sim 24 - 46 % ) and irregular systems ( \sim 17 - 39 % ) .
The only ERO detected in the radio is likely to host an obscured AGN .
The average radio luminosity of the star-forming EROs undetected in the radio implies star formation rates of the order of \sim 33 M _ { \odot } yr ^ { -1 } .
The colors , redshifts and masses of the E/S0 galaxy subsample imply a minimum formation redshift z _ { f } \sim 2 .
With this z _ { f } 
there is enough time to have old and massive stellar spheroids already assembled at z \sim 1 .
We verify that the R - K _ { s } vs . J - K _ { s } color diagram is efficient in segregating old and dusty-star-forming EROs .