  We present here our results on the hour like time scale X-ray flux variations
in a sample of active galactic nuclei using data from the Nuclear Spectroscopic
Telescope Array (NuSTAR). We find that in the 3-79 keV band, BL Lacs are more
variable than flat spectrum radio quasars and Seyfert galaxies. Among Seyferts,
Seyfert 2s are more variable than Seyfert 1s. Also, radio-loud quasars are more
variable in the hard (10-79 keV) band than the soft (3-10 keV) band while,
Seyfert galaxies tend to show more variations in the soft band relative to the
hard band.
