Alkaline copper quat (ACQ) is an established wood preservative that is formulated with solubilized copper in amine solvent. This article describes three separate trials in Australia that investigated whether substituting soluble copper with micronized copper affects performance. ACQ and micronized copper quat (MCQ) performed similarly in Pinus radiata against four brown-rot fungi in a soil-block bioassay, while MCQ performed slightly better against two white-rot fungi in Eucalyptus delegatensis. A 2.3-year in-ground stake trial in the wet tropics at Innisfail also found that ACQ and MCQ performed comparably in P. radiata and Corymbia maculata. This was a severe test site with attack caused by soft-rot fungi, white-rot fungi, and termites. An H3 (outside, aboveground) field test against termites in Darwin showed that ACQ- or MCQ-treated P. radiata and C. maculata performed similarly against Coptotermes acinaciformis and Mastotermes darwiniensis. These trials demonstrated that MCQ performs comparably to ACQ under the test conditions used.