Two novel compounds [(CH 3 ) 4 N] 3.5 H 1.5 [PW 11 O 39 Ca(H 2 O) 2 ]·3H 2 O 1 and [(CH 3 ) 4 N] 3.5 H 1.5 [PW 11 O 39 Sr(H 2 O) 2 ]·1.5H 2 O 2 based on lacunary Keggin-type phosphotungstate, have been synthesized by moderate temperature reaction in water and characterized by IR, TG, UV spectra, and X-ray single-crystal diffraction. X-ray single-crystal structural analysis reveals that the adjacent polyanions are polymerized to form a 1D infinitely linear chains by the bridging WO t M(M=Ca, Sr). The Ca(Sr) coordination cations occupy the vacant site of the [α-PW 11 O 39 ] 7− subunit and are heptacoordinate with a distorted monocapped trigonal prismatic environment.