From gas coals to anthracites, 16 different rank coals were carbonized at 3degreesC/min in crucible. Chars and cokes produced at different temperatures were analyzed by x-ray diffraction; their true relative density and micro-strength were also measured. The true relative density of all chars produced by different rank coals increases as temperature increases. As the coals volatile increase, cokes true relative density goes down linearly. Cokes produced by weakly caking coals have the lowest true relative density, but have almost the highest micro-strength with anthracites. X-ray diffraction showed chars produced by weakly-caking coal have the largest d(002) and least L-C in all chars. Coke structure approaching graphic carbon has high true relative density and low micro-strength, while coke structure approaching non-graphic carbon has low true relative density and high micro-strength.