This paper presents the solution for the problem of oblique wave diffraction by the thick barriers in the presence of surface tension. Two different barrier configurations are considered namely, (i) bottom standing thick rectangular barrier, (ii) thick rectangular block. Reflection and transmission coefficients are evaluated by applying an appropriate multi-term Galerkin approximation technique. The basis functions are chosen in terms of the Gegenbauer polynomial of order 1/6 with suitable weights. For each configuration, reflection and transmission coefficients are represented graphically against wave numbers in many figures by varying surface tension. The numerical solutions are compared with known results without the effect of surface tension. Thus, good agreement of the results implies the correctness of the present method. The effect of surface tension at the free surface is investigated by analyzing the reflection and transmission coefficients. It can be observed that surface tension plays a qualitatively relevant role in the present study. © 2021, Indian Association for the Cultivation of Science.