  We report on the properties of halo coronal mass ejections (HCMEs) in solar
cycles 23 and 24. We compare the HCMEs properties between the corresponding
phases (rise, maximum, and declining) in cycles 23 and 24 in addition to
comparing those between the whole cycles. Despite the significant decline in
the sunspot number (SSN) in cycle 24, which dropped by 46% with respect to
cycle 23, the abundance of HCMEs is similar in the two cycles. The HCME rate
per SSN is 44% higher in cycle 24. In the maximum phase, cycle-24 rate
normalized to SSN increased by 127% while the SSN dropped by 43%. The source
longitudes of cycle-24 HCMEs are more uniformly distributed than those in cycle
23. We found that the average sky-plane speed in cycle 23 is ~16% higher than
that in cycle 24. The size distributions of the associated flares between the
two cycles and the corresponding phases are similar. The average speed at a
central meridian distance (CMD) = 600 for cycle 23 is ~28% higher than that of
cycle 24. We discuss the unusual bump in HCME activity in the declining phase
of cycle 23 as due to exceptional active regions that produced many CMEs during
October 2003 to October 2005. The differing HCME properties in the two cycles
can be attributed to the anomalous expansion of cycle-24 CMEs. Considering the
HCMEs in the rise, maximum and declining phases, we find that the maximum phase
shows the highest contrast between the two cycles.
