In this article, the collocated parameter models are used to estimate the effective thermal conductivity of the two-phase materials. The algebraic equations are derived using a unit-cell-based isotherm approach for a two- and three-dimensional spatially periodic medium. The geometry of the medium is considered as matrix of touching and nontouching in-line square and circular cylinders as well as touching and nontouching in-line solid and hollow cubes. The models are used to predict the thermal conductivity of numerous two-phase materials (maximum conductivity ratio of 1000 and concentration ranging between 0 and 1). The estimated thermal conductivity data is in good agreement with experimental data within 16.67% deviation for various two-phase systems. The results are compared with the standard models and experimental data for different types of two-phase systems; it is shown that the touching in-line solid cube model predicts better as compared to other geometrical configurations.