PopStar: A new grid of Evolutionary Synthesis Models in the Virtual Observatory

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.