A freeze dried kit formulation for the preparation of 99mTc-labelled IOR-CEA1, a monoclonal antibody (MoAb) against a human colorectal cancer, was developed. Methods of analysis were also established permitting identification of radiochemical impurities which may be present in radiopharmaceutical solution. 99mTc-EHDP-MoAb-IOR CEA1 prepared by the kit method was evaluated in human volunteers to apply the radioimmunodetection of human colon cancer. Data demonstrated that the complex formed after kit-reconstitution shows excellent stability and tumor seeking properties. Colon carcinoma in patients was successfully detected 6–8 and 20–28 h post administration.