Carbon nanotubes have been increasingly used in the fields of nanorobotics, electrochemical
catalysis, microarray chips, and green adsorbents for pollutants, sensors and optoelectronics. Complicated
physico-chemical aspects and novel schemes to synthesize controlled featured carbon nanotubes have added new ambiguities
to their characterizations and applications and these must be resolved on an urgent basis. Most of the characterization
tools such as scanning electron microscopy, transmission electron microscopy, scanning tunneling microscopy and atomic
force microscopy probes only for characterizing the local features of carbon nanotubes. However, X-ray powder diffraction
can reveal the local and global features of microstructure’s lattice and crystalline phases, domain sizes, and impurities.
Thus it is worthwhile to highlight this technique for better understanding and utilization of its benefit to unravel the
carbon nanotube ambiguities. To the best of our knowledge, no comprehensive reviews or systematic description of X-ray
powder diffraction on carbon nanotubes characterization have been published yet. In this review, we filled-up this gap and
provided a systematic presentation of X-ray powder diffraction application in carbon nanotubes characterization. This
could be used as a reference guide for the utilization of X-ray powder diffraction to probe the various features of carbon
nanotubes and carbon nanotubes based materials.