A new nanocrystalline TiO2-polymer composite with high volume particle loading has been developed for matching layers of ultra high frequency medical ultrasonic transducers. The composite consists of 25 nm size TiO 2 particles and Epoxy resin with the acoustic impedance reaching as high as 7.19 MRayls. Ultrasonic spectroscopy methods are used to measure the ultrasonic velocity of the composite thin film with thickness ∼8 microns. It is found that the acoustic impedance can be increased by annealing the composite at higher temperatures. Our measured results show that this new composite has good acoustic impedance characteristics that are needed for matching layers of ultra-high frequency transducers.