ESA has recently decided to put more effort in the development of the Virtual Observatory (VO). This effort will be based at ESAC where most of ESA's current astronomy missions archives are already located. There was created the ESA VO Project, which is a natural extension of the Archive and VO work already carried out at ESAC. Tasks included making the ISO and XMM-Newton archives VO complian through SIAP and SSAP VO protocols as well as developing some VO tools, like VOSpec, which handles spectra coming from VO SSAP compliant servers.