Mesocrystals are one kind of self-assembled superstructures from nanocrystals in crystallographic ordered way, often showing single-crystal-like electron diffraction behaviors. The formation process of mesocrystals imposes a great challenge to classic crystallization theory and their unique structural features of nanocrystals aggregations may create enhanced and new properties, which drive researchers to make extensive studies. This paper reviews the latest progress in the preparation methods, properties and applications of mesocrystals. The synthesis methods of mesocrystals mainly include coprecipitation, hydrothermal, solvothermal, topological conversion, electrochemical, dissolution and recrystallization methods. And catalytic, electrochemical, optical and electrical properties as well as biomedical applications of mesocrystals are exhibited. The formation process and structure-property relationships of mesocrystals are emphasized. Besides, some scientific issues about the preparations, properties and applications of mesocrystals are pointed out, and the outlook of further development in the field of mesocrystals is also given.

Contents
1 Introduction
2 Synthesis of mesocrystals
2.1 Coprecipitation methods
2.2 Hydrothermal methods
2.3 Solvothermal methods
2.4 Topological conversion methods
2.5 Electrochemical methods
2.6 Dissolution and recrystallization methods
3 Properties and applications of mesocrystals
3.1 Catalytic properties
3.2 Electrochemical properties
3.3 Optical and electrical properties
3.4 Biomedical applications
4 Conclusion and outlook