We present the results of an optical photometry and high-resolution spectroscopy campaign for a modest sample of X-ray selected stars in the Chamaeleon and Rho Ophiuchus star-forming regions. With R similar to 50 000 optical spectra, we establish kinematic membership of the parent association and confirm stellar youth for each star in our sample. With the acquisition of new standardized BVIc photometry, in concert with near-infrared data from the literature, we derive age and mass from stellar positions in model-dependent Hertzsprung-Russell diagrams. We compare isochronal ages derived using colour-dependent extinction values finding that, within error bars, ages are the same irrespective of whether E(B - V), E(V - Ic), E(J - H) or E(H - K) is used to establish extinction, although model ages tend to be marginally younger for redder E-colour values. For Cham I and eta Cham members, we derive ages of less than or similar to 5-6 Myr, whereas our three eta Cha candidates are more consistent with a greater than or similar to 25 Myr post-T Tauri star population. In Rho Ophiuchus, most stars in our sample have isochronal ages < 10 Myr. Five objects show evidence of strong infrared excess (Lambda nu > 5) in the Two Micron All Sky Survey colour-colour diagram, however in terms of H alpha emission, all stars except RXJ1625.6-2613 are consistent with being weak-lined T-Tauri stars. Spectral energy distributions (SEDs) over the range similar or equal to 4000 angstrom < lambda < 1000 mu m, show that only one Chamaeleon star (RXJ1112.7 -7637) and three Rho Ophiuchus stars (ROXR1 13, RXJ1625.6-2613 & RXJ1627.1-2419) reveal substantial departures from a bare photosphere.