This table contains results from the analysis of a sample of 383 X-ray selected galaxy groups and clusters with spectroscopic redshift measurements (up to z ~ 0.79) from the 2XMMi/SDSS Galaxy Cluster Survey. The X-ray cluster candidates were selected as serendipitously detected sources from the 2XMMi-DR3 catalog that were located in the footprint of the Sloan Digital Sky Survey (SDSS-DR7). The cluster galaxies with available spectroscopic redshifts were selected from the SDSS-DR10. The authors developed an algorithm for identifying the cluster candidates that are associated with spectroscopically targeted luminous red galaxies and for constraining the cluster spectroscopic redshift. A cross-correlation of the constructed cluster sample with published optically selected cluster catalogs yielded 264 systems with available redshifts. The present redshift measurements (presented in reference paper III) are consistent with the published values. The current cluster sample extends the optically confirmed cluster sample from the authors' cluster survey by 67 objects. Moreover, it provides spectroscopic confirmation for 78 clusters among their published cluster sample, which previously had only photometric redshifts. Of the new cluster sample that comprises 67 systems, 55 objects are newly X-ray discovered clusters and 52 systems are sources newly discovered as galaxy clusters in optical and X-ray wavelengths. Based on the measured redshifts and the fluxes given in the 2XMMi-DR3 catalogue, the authors have estimated the X-ray luminosities and masses of the cluster sample. This table contains 145 entries, 67 of which are new (as of Paper III) optically confirmed clusters (marked by values of ref_source = 'Paper III') and 78 of which are clusters from Paper II which have now been spectroscopically confirmed (marked by values of ref_source = 'Paper II'). The tabular information on the 530 clusters that was presented in Paper II of this set of papers is available as the HEASARC <a href="/W3Browse/xmm-newton/xmmsdssgcs.html">XMMSDSSGCS table</a>). The following parameters were obtained from the current optical-band cluster detection algorithm: sdss_dr10_bcg_id, sdss_dr10_bcg_ra, sdss_dr10_bcg_dec, bcg_rmag, redshift, num_spect_members, phot_redshift, num_phot_members, and spatial_offset. This table was created by the HEASARC in July 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/564/A54">CDS catalog J/A+A/564/A54</a> file table1.dat. This is a service provided by NASA HEASARC .