Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. A total of 23 bat day-roosts were identified to tree and used by 18 bats (10 male; 8 female; 17 adult; 1 juvenile). Three maternity roosts were confirmed. One maternity roost was determined to be a bat that was not captured or radio-tagged but was visually located in a roost tree that was also in use by a radio-tagged bat. During the period of monitoring of telemetered bats (less than one month), multiple roosts were located for five bats. Twelve roost sites were located in Hawaii State administered lands, with the rest on private property. Trees used by roosting bats were primarily comprised of non-native plantation or invasive species, although native Metrosideros polymorpha was used in three cases. Tree height and canopy cover ranged from 9 to 56 m (mean = 21 m) and 3 to 97% (mean = 45%). Of the 13 bats visible at perch in the roost, metrics of roost perch canopy cover, perch height and perch aspect ranged from 4 to 98% (mean = 50%), 5 to 24 m (mean = 14 m), and 110 (east-southeast) to 334 (north-northwest) degrees (mean = 217 degrees [southwest]), respectively. Distance to the nearest tree ranged from 0.5 to 22 m (mean = 6 m).