  We present a new set of theoretical evolutionary synthesis models, PopStar.
This grid of Single Stellar Populations covers a wide range in both, age and
metallicity. The models use the most recent evolutionary tracks together with
the use of new NLTE atmosphere models for the hot stars (O, B, WR, post-AGB
stars, planetary nebulae) that dominate the stellar cluster's ionizing spectra.
The results of the models in VO format can be used through VOSpec.
