The pyroelectric coefficients of 0.72Pb(Mg1/3Nb2/3)O-3-0.28PbTiO(3) (PMN-28PT), 0.67Pb(Mg1/3Nb2/3)O-3-0.33PbTiO(3) (PMN-33PT), and 0.92 Pb(Zn1/3Nb2/3)O-3-0.08PbTiO(3) (PZN-8PT) single crystals, oriented and poled along three different crystallographic directions, (C), (C), and (C), have been measured using a dynamic method. The suffix C indicates reference to the prototypic cubic coordinate system. Large coefficients of up to 1070 mu C m(-2) K-1 have been observed for the (C) oriented, rhombohedral PMN-28PT and PMN-33PT samples, where the measurement direction corresponds to the polar axis of the crystal. For each composition and orientation two different poling procedures are compared, a commonly used field cooling method and a low temperature poling protocol. It was found that in otherwise pseudoorthorhombic samples of PZN-8PT, a room temperature rhombohedral phase could be stabilized by application of a field along the (C) direction while heating from -70degreesC. (C) 2004 American Institute of Physics.