The z -GAL survey observed 137 bright Herschel -selected galaxies with the IRAM Northern Extended Millimeter Array (NOEMA) to measure their spectroscopic redshift. It detected several multiple sources and secured the spectroscopic redshift of a total of 165 individual galaxies over the range 0.8 < z < 6.5. The wealth of information provided by the NOEMA spectra allowed us to study the physical properties of these galaxies. By modelling their spectral energy distributions, we determined their dust mass, M dust , temperature, T dust , and emissivity index, β dust and found a significant anti-correlation between T dust and β dust . Using the detected 12 CO lines, we derived the molecular gas mass of the z -GAL sources. Combining the molecular lines and the dust continuum emission, we computed their gas depletion timescales, τ dep : the z -GAL sample consists mainly of powerful starbursts with τ dep in the range between 0.1 and 1.0 Gyr, while only ~ 25% belongs to the ‘main sequence’ of star forming galaxies.