  We present the spectrophotometric properties of a sample of 141 emission-line
galaxies at redshifts in the range $0.2<z<1.0$ with a peak around
$z\in[0.2,0.4]$. The analysis is based on medium resolution
($R\_{\mathrm{s}}=500-600$), optical spectra obtained at VLT and Keck. The
targets are mostly {} "Canada-France Redshift Survey" emission-line galaxies,
with the addition of field galaxies randomly selected behind lensing clusters.
We complement this sample with galaxy spectra from the {} "Gemini Deep Deep
Survey" public data release. We have computed absolute magnitudes of the
galaxies and measured the line fluxes and equivalent widths of the main
emission/absorption lines. The last two have been measured after careful
subtraction of the fitted stellar continuum using the \texttt{platefit}
software originally developed for the SDSS and adapted to our data. We present
a careful comparison of this software with the results of manual measurements.
The pipeline has also been tested on lower resolution spectra, typical of the
{} "VIMOS/VLT Deep Survey" ($R\_{\mathrm{s}}=250$), by resampling our medium
resolution spectra. We show that we can successfully deblend the most important
strong emission lines. These data are primarily used to perform a spectral
classification of the galaxies in order to distinguish star-forming galaxies
from AGNs. Among the initial sample of 141 emission-line galaxies, we find 7
Seyfert 2 (narrow-line AGN), 115 star-forming galaxies and 16 {} "candidate"
star-forming galaxies. Scientific analysis of these data, in terms of chemical
abundances, stellar populations, etc, will be presented in subsequent papers of
this serie.
