We characterize the molecular gas content (ISM cold phase) using CO emission of a redshift-limited subsample of isolated galaxies from the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) project in order to provide a comparison sample for studies of galaxies in different environments. We present the ^12^CO(1-0) data for 273 AMIGA galaxies, most of them (n=186) from our own observations with the IRAM 30m and the FCRAO 14m telescopes and the rest from the literature. We constructed a redshift-limited sample containing galaxies with 1500km/s<v<5000km/s and excluded objects with morphological evidence of possible interaction. This sample (n=173) is the basis for our statistical analysis. It contains galaxies with molecular gas masses, MH2, in the range of ~10^8^-10^10^M_{sun}_. It is dominated, both in absolute number and in detection rate, by spiral galaxies of type T=3-5 (Sb-Sc). Most galaxies were observed with a single pointing towards their centers. Therefore, we performed an extrapolation to the total molecular gas mass expected in the entire disk based on the assumption of an exponential distribution. We then studied the relationships between MH2 and other galactic properties.