Exotic nuclei produced via projectile fragmentation were separated in flight by the fragment separator FRS and injected into the storage ring ESR at (300-400) MeV/u. Ultra-cold fragment beams with half-lives larger than 10 s were investigated by Schottky Mass Spectroscopy (SMS) applying electron cooling. A new efficient data acquisition system recorded the time correlations allowing corrections for possible drifts of the revolution frequencies In addition, it allows to observe the nuclear decay of the fragments circulating in the ESR. Representative results of previously unknown masses of about 150 neutron-deficient isotopes in the range of 52 ≤ Z ≤ 85 are discussed. Results for lead isotopes are compared with different mass models. Exotic nuclei with half-lives shorter than the time required for electron cooling have been investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique gives access to all nuclei with half-lives down to the microsecond range and has been successfully applied in first experiments with light fragments produced by 52Cr and 84Kr projectiles. A mass resolving power of better than ℳ/Δℳ = 0.9 · 105 (FWHM) was achieved with isochronous mass spectrometry (IMS).