... This paper describes distortion calibration procedures for the SOHO /LASCO-C2 Coronagraph, based on in-orbit data and extensive image processing methods. ... C2 suffers from moderate optical distortion, which must be corrected in order to properly locate the stars crossing its field-of-view (which are subsequently used for photometric calibrations), to retrieve critical attitude parameters, and to insure a correct overlapping of the region common to the C2 and C3 instruments. ...