Accurate measures of species abundance and distribution underpin effective wildlife management and conservation strategies. Obtaining these data is very challenging when researching the cryptic nocturnal arboreal mammals of in the dense forest of the Wet Tropics. Our research shows that using a hand-held thermal imager significantly increases the detection rate of all mid-sized arboreal mammals when compared to the most commonly used method of spotlighting. We determine the optimal environmental and mechanical parameters for thermal imaging, and we investigate ‘cost-versus-result’ of hand-held imaging devices currently available on the market. We suggest that hand-held thermal imaging is a great emerging technology for cryptic arboreal mammal detection across tropical forested regions and beyond.