In this work liquid phase one-step synthesis of acacetin from ethyl 3-(4-methoxyphenyl)-3-oxopropionate and phloroglucinol using PEG 1000 as solvent was examined. Heating of the reaction mixture was done with 915 MHz and 2.45 GHz microwaves at atmospheric pressure. The demethylation of the obtained acacetin using HBr at reflux led to the formation of apigenin. In view of a possible scale-up, the reaction conditions under 915 MHz microwaves were optimized to obtain high yields of acacetin. The energy required to convert phloroglucinol in acacetin was also estimated and used to calculate the total microwave power required for scaling up the process by a factor of 100. This method is an easier and cleaner synthesis for large scale preparation of flavones with good yields and purity. (C) 2017 Elsevier B.V. All rights reserved.