A major safety concern addressed during the design of the water-cooled lead-lithium (PbLi) breeding blanket (BB) is represented by an in-box loss-of-coolant accident, where high-pressure water is supposed to interact with PbLi inside the BB. Code development activities are being carried out to create the needed tools for the safety analysis of these systems in the case of incidental scenarios, which are supported by extensive experimental campaigns that aim at providing data for SIMMER code verification and validation (V&V). In this regard, the present work aims at presenting the dataset generated during the Series D experimental campaign performed at the LIFUS5/Mod3 facility operated at the ENEA Brasimone Research Centre. This is a separate effect facility able to simulate the mixing of water and PbLi alloy in conditions of temperature and pressure similar to the ones encountered by the system during nominal operation and to acquire significant data on all the relevant thermochemical parameters. Moreover, a preliminary analysis of the data has been performed to critically determine the quality of the data and to identify possible issues in the experimental process. In the end, the foreseen extension of the experimental work is described, as well as the foreseen application of the acquired data in the code V&V activities.