From September 23 to 26, 2019, the 6th International Symposium on Monolayer Protected Clusters (ISMPC19) were held on the campus of XMU. The symposium was co-organized by the College of Chemistry and Chemical Engineering, Xiamen University and Collaborative Innovation Center of Chemistry for Energy Materials. The opening ceremony was chaired and addressed by Prof. Zheng Nanfeng, a Changjiang Chair Professor at Xiamen University. Over 150 participants from 50 institutions at home and abroad including world leading researchers in the field of monolayer-protected metal clusters were gathered to discuss the latest developments in the field of monolayer protected metal clusters and define possible future avenues. Monolayer-protected metal clusters in the size-regime of 10–300 metal atoms are a special class of materials that are currently the focus of interest, both for fundamental reasons and for their use in possible applications. This symposium series was organized first twice in Finland (2008 & 2011) and then in the USA (2013), Japan (2015), and Switzerland (2017).