In this work are studied the pyroelectric and photoacustic properties of Pb-0.88(Ln)(0.08)Ti0.98Mn0.02O3 (Ln = La, Sm, Eu) ferroelectric ceramic system. These type of ferroelectric ceramics presents high values in the following characteristics: dielectric constant, Curie temperature, electromechanical anisotropy, and frequencies of operation. These properties make them useful for applications such as: the detection of infrared radiation, ultrasonic transducers for biomedical applications. The relationship between dielectric constant and temperature measurements as well as pyroelectric measurements using the technique of Byer-Roundy were performed. Values of the pyroelectric coefficient and figure of merit for infrared detector materials were obtained. Also the photoacustic spectra of the samples was obtained.