Iron oxide particles are attracting a lot of attention in science and industry as they are used in many fields such as biotechnology, biochemistry, and medicine. They can be prepared by many different methods. The latest and most used method is microwave synthesis. It is characterized by simplicity, speed, and the ability to precisely control the synthesis conditions. This paper gives a brief insight into the process of hydrothermal microwave synthesis of iron oxide particles under very specific experimental conditions, by hydrolysis of iron(Ⅲ) salt or iron(Ⅲ) salt and iron(Ⅱ) salt in the ratio of 1:2. In addition, the influence of essential oils of chamomile, broom and lavender on the synthesis products was studied. It has been proved that microwave synthesis with iron(Ⅲ) chloride at 200 °C in a period of 20 minutes forms hematite particles, and the addition of essential oils of broom and chamomile under the same synthesis conditions produces a mixture of hematite and goethite. Microwave synthesis with iron(Ⅲ) and iron(Ⅱ) salt in a ratio of 1:2, produces magnetite particles at 200 °C in 10 minutes. The addition of lavender essential oil to the same synthesis showed no effect on the final synthesis product. FTIR spectroscopy was used to characterize the obtained particles.