The superconducting gap structure is an unresolved issue in most of unconventional superconductors. Here we measured the thermal conductivity of 2D unconventional superconductors, spin-triplet Sr2RuO4, heavy fermion CeCoIn5 and organic kappa-(BEDT-TTF)(2)Cu(NCS)(2), in magnetic field rotating within the 2D planes. On the basis of the angular variation in the thermal conductivity, we demonstrate that the gap function is d(k) = Delta(0)(z) over cap (k(x) + ik(y))(cos ck(z) + alpha) for Sr2RuO4, d(x2-y2) for CeCoIn5, and d(xy). for kappa-(BEDT-TTF)(2)Cu(NCS)(2). (C) 2002 Elsevier Science Ltd. All rights reserved.