This data publication contains the results of three separate moisture tests on masticated fuels collected from mixed-conifer forests in 14 study locations. These data were collected from 2012 through 2016 as part of the MASTIDON project. The MASTIDON project was a four-year research project to study how masticated material differs when treated with different cutting machines and how the masticated particles decompose when left on the ground for multiple years. It investigated masticated materials in four states of the western United States. The project was funded by the Joint Fire Sciences Program (JFSP) and RMRS between 2013 and 2016. The masticated particles within this project were created by four different machines, including a vertical rotating head, horizontal drum, chipper, and mower. They had been decomposing in situ in wet and dry areas of Idaho, Colorado, New Mexico, and South Dakota since their initial treatment. This portion of the study was designed to show how these materials absorb or lose water under three different conditions. This data publication includes the experimental results of tests conducted in (1) a temperature and humidity controlled environmental chamber; (2) outside under variable temperature and humidity conditions; and (3) in a temperature-controlled oven under laboratory conditions. The environmental chamber and outdoor tests were conducted on the entire range of fuel loads using 25 x 25 centimeter wire cages containing duff, 1 hour fuels, 10 hour fuels, 100 hour fuels, a variety of sizes of bark, and fresh litter materials. The oven tests were conducted on individual particles that were mostly 10 hour fuel-size class (i.e., between 7 millimeter and 2.54 centimeter in diameter). This publication also includes files describing the MASTIDON project and its goals.