Ultrasonic measurements on a single crystal of the intermetallic compound Lu5Ir4Si10 are presented. Large anomalies in the velocity and ultrasonic attenuation of the elastic modes are observed at the structural phase transition TS∼80 K. The velocity of the longitudinal C11 and C33 mode exhibits a second order transition behavior. In contrast the velocities of the shear C44 and C66 modes exhibit a first order transition behavior. The longitudinal C11 mode is strongly coupled to the ordering system below TS. Similarities in the longitudinal elastic anomalies with known reduced dimensional charge density wave systems suggest that the nature of the structural phase transition TS in Lu5Ir4Si10 could be associated with a charge density wave phase transition. •Charge density wave phase transition.•First order phase transition.•Elastic constants.