EXHIBIT 99.1 CONSENT OF SOLOMON ASSOCIATES We hereby consent to the use in the 2001 Form 10-K for Conoco Inc., of our name in reference to ranking of the performance of Conoco's Asian, European and United States refineries which appear in such 2001 Form 10-K, to be filed on or about March 15, 2002. We also consent to the reference to us as "an independent benchmarking company." /s/ D. B. Bossung Executive Vice President Solomon Associates, Inc. February 7, 2002