Compaction responses have been carried out to characterize the architectural and mechanical performance of carbon nanotube (CNT) agglomerates efficiently. The agglomerate density, agglomerate strength and internal pressure were obtained quantitatively, and the relationships between them were discussed. Agglomerates were classified into soft and hard agglomerates by strength. Hard agglomerates and soft agglomerates dominated double walled CNTs and aligned multi-walled CNT arrays respectively while both hard and soft agglomerates dominated conventional multi-walled CNTs. The microstructures and interaction between CNTs were discussed to explain the different agglomerate behaviors. (C) 2011 Elsevier B.V. All rights reserved.