Amphibious and aquatic soft robotic systems have numerous applications and functionalities, such as land and underwater exploration, search-and-rescue, and shore and oceanic environmental cleaning (e.g. garbage collection), just to name a few. For such robotic systems to execute diversified modes of locomotion and tasks, they will need to have the ability to crawl, walk, and swim, as well as to grasp, fetch, sample and manipulate surrounding objects. Hierarchical fibrillar structures have been shown to be advantageous when grasping objects of different size, shape, and topography. Through the integration of such structures on the exterior of a soft robot, a great amount of conformity and continuous adhesive force can be accomplished in a controlled manner. For instance, by lining fibrillar structures in a soft cavity membrane, pneumatic systems can convex the membrane for fiber attachment and return to the initial configuration for detachment. Considering that such grippers may be utilized in diverse applications and environmental conditions (e.g. different temperature and saturation), it is vital to analyze them in such conditions. This study will focus on adhesive properties of fibrillar structures made of different materials against a wide range of temperatures in both dry and wet environments. The following materials will be considered for fabricating the fibers: polydimethylsiloxane (PDMS) and polyurethane acrylate (PUA), for their known performance in both dry and wet conditions. A friction/adhesion characterization setup will be used to examine the adhesive forces of the synthetic fibers under dry, moist, and fully saturated conditions at different temperature ranges. While fibrillar structures have been shown to conform and adhere to various surface topographies, this study will initially consider flat objects to characterize the performance of different materials. Through analyzing adhesive properties under varied environmental conditions, superior fibrillar material can be selected for a diversified set of applications. The findings will be essential in the development of amphibious and aquatic soft robotic systems.