Collision strengths for 4005 transitions among the lowest 90 levels of the (1s^2^2s^2^2p^6^) 3s^2^3p^5^, 3s3p^6^, 3s^2^3p^4^3d, 3s3p^5^3d and 3s^2^3p^3^3d^2^ configurations of Fe X have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2005, Comput. Phys. Commun. , in prep.), over a wide energy range up to 210Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 10^7^K. The present calculations should represent a significant improvement (in both range and accuracy) over the earlier available results of Bhatia & Doschek (1995, At. Data Nucl. Data Tables, 60, 97), Tayal (2001ApJS..132..117T) and Pelan & Berrington (2001A&A...365..258P). Based on several comparisons, the accuracy of our data is assessed to be better than 20%, for a majority of transitions.