Exploring high-

We present simulated observations of galaxies at z = 2 and z = 3 to probe the capabilities of next-generation telescopes (E-ELT and JWST) to measure the structural and photometrical properties of high-redshift galaxies. We carry out an extensive set of simulations of high-redshift galaxies adopting the specifications of the E-ELT first light instrument MICADO. The main parameters (sizes, Sersic index, and magnitudes) of the galaxies are measured using GALFIT and the accuracy of the determinations is assessed by comparing the input values to the measurements from many runs with different statistical noise. We also address the effects on the accuracy of the measurements of possible spatial variation of the point spread function (PSF) in the field. We find that from 3h exposure E-ELT near-infrared (IR) images of galaxies at z ~ 2 and z ~ 3 it will be possible to measure the size, total magnitude, and galaxy morphology with an accuracy of 2−5% for objects as faint as H ~ 25 and half-light size of 0.2 arcsec. The effective radius of compact, early-type galaxies is also recovered with ~5% accuracy, provided that their half-light size exceeds 20 mas. These results are compared with those expected from simulated observations obtained with NIRCam on board the JWST