Technical Abstract: With an annual production of approximately 6.5 billion gallons of fuel ethanol, and projected growth for the foreseeable future, supplies of coproducts such distillers dried grain with solubles (DDGS) are anticipated to continue to grow as well. DDGS is used primarily as livestock feed. Much of the DDGS must be shipped, often over large distances throughout the country, as much of the livestock (especially large dairies and feedlots) are outside the Corn Belt, where most of the ethanol plants are currently located. ¿Caking¿, or stickiness, among particles is an important issue related to DDGS, especially when it leads to flowability problems when it is stored and shipped, this problem needs to be alleviated. Towards that end, the objective of this study was to understand the surface nature and characteristics of DDGS particles. The study examined the distribution patterns of chemical components of DDGS particles using standard staining biological techniques and stereo light microscopy. Surface chemical composition was also studied using confocal laser microscopy. Cross sectional staining of DDGS particles indicated a higher amount of protein thickness versus carbohydrate thickness in surface layers from DDGS that had lower flow function index, and thus greater cohesiveness, which indicates possible flow problems. Additionally, surface fat staining suggests that higher surface fat also occurred in samples with worse flow problems.