In a first experiment with accelerated beams at TRIUMF-ISAC, the scattering of radioactive Na-21 (T-1/2=22.49 s) on protons has been investigated. Na-21 beams of typically 5x10(7) particles/s were employed while center-of-mass energies from 0.45 to 1.4 MeV were scanned and spectra with high statistics were collected. The experiment was carried out using large area silicon detectors at the TUDA facility. Three strong resonances corresponding to states in Mg-22 have been identified at energies of 830 keV, 1115 keV, and 1311 keV, respectively. Using these data, aspects of the T=1, A=22 mirror system and the s-wave component of the astrophysically important Na-21(p,gamma)Mg-22 reaction are discussed.