Heavy oil and bitumen are likely to be among the dominant fossil fuels available as energy sources during the next several decades. The “tar sands” of western Canada are prominent among these. Our research group is developing techniques for bitumen upgrading that include the modification of the feed by combining mild thermal cracking followed by adsorption of the modified heavy molecules, over tailor-designed adsorbents and catalysts. Understanding the adsorption phenomena is of paramount importance in this work. This paper will present adsorption results obtained with heavy molecules such as asphaltenes fractions isolated from Northern of Alberta bitumens, virgin and thermal cracked products. Solids examined include kaolin, silica-alumina, clay minerals, real sample from Athabasca reservoir and modified petroleum cokes. The absorption behavior of these solids and preliminary correlations established among adsorption phenomena and adsorbate properties are discussed.