X-ray crystal structures of the inclusion complexes of calix[4]arene monomethoxy-carboxylic acid 1 (C30H26O6) with acetontrile and acetone are reported. The crystal of C30H26O6 center dot CH3CN is of monoclinic, space group P2(1)/c with a = 11.691(5), b = 13.753(5), c = 17.072(7) angstrom, beta = 100.104(7)degrees, C32H29NO6, M-r = 523.56, V = 2702.4(18) angstrom(3), Z = 4, D-c = 1.287 g/cm(3), mu(MoK alpha) 0.089 mm(-1), T = 293(2) K, 5570 independent reflections with 3220 observed ones (I > 2 sigma(I)), R 0.0521 and wR = 0. 1132 with GOF = 1.042 (R = 0. 1055 and wR = 0.1350 for all data). The data for C30H26O6 center dot CH3COCH3: monoclinic, space group P2(1)/c, a = 12.366(4), b = 12.119(4), c = 18.796(6) angstrom, beta = 90.871(6)degrees, C33H32O7, M-r = 540.59, V = 2816.6(16) angstrom(3), Z = 4, D-c = 1.275 g/cm(3), mu(MoK alpha) = 0.089 mm(-1), T = 293(2) K, 5783 independent reflections including 2580 observed ones (I > 2 sigma(I)), R = 0.0555 and wR = 0.1424 with GOF = 0.975 (R = 0.1601 and wR = 0.1884 for all data). Their architectures exhibit one-dimensional inclusion polymers which are mediated head-to-tail by the guests.