Microwave (MW) was applied to enhance chlorobenzene (CB) removal using commercial micron iron (mu-Fe) particles, nanoscale iron particles (nC-Fe-0), and nanoscale iron particles freshly prepared in our laboratory (nP-Fe-0) as the dielectric media. CB solution irradiated with 250 W MW for 150 s achieved better CB removal than without MW irradiation, because MW radiation increased the iron oxidization rate, surface activity, and hence, the CB removal rate. MW-induced iron particles were capable of removing 13.6 times (61.2% vs. 4.5% for mu-Fe), 2.8 times (76.5% vs. 27.5% for nP-Fe-0), and 3.6 times (65.4% vs. 18.1% for nC-Fe-0) more CB, and the CB activation energy decreased to 16.8 kJ/mol (mu-Fe), 3.3 kJ/mol (nP-Fe-0), or 3.5 kJ/mol (nC-Fe-0). MW-induced iron particles can potentially decompose toxic organic substances as demonstrated in this laboratory study.