Grid computing is a hardware and software infrastructure and provides affordable, sustainable, and reliable access. Its aim is to create a supercomputer using free resources. One of the challenges to the Grid computing is scheduling problem which is regarded as a tough issue. Since scheduling problem is a non-deterministic issue in the Grid, deterministic algorithms cannot be used to improve scheduling. In this paper, a combination of imperialist competition algorithm (ICA) and gravitational attraction is used for to address the problem of independent task scheduling in a grid environment, with the aim of reducing the makespan and energy. Experimental results compare ICA with other algorithms and illustrate that ICA finds a shorter makespan and energy relative to the others. Moreover, it converges quickly, finding its optimum solution in less time than the other algorithms Grid computing is a hardware and software infrastructure and provides affordable, sustainable, and reliable access. Its aim is to create a supercomputer using free resources. One of the challenges to the Grid computing is scheduling problem which is regarded as a tough issue. Since scheduling problem is a non-deterministic issue in the Grid, deterministic algorithms cannot be used to improve scheduling. In this paper, a combination of imperialist competition algorithm (ICA) and gravitational attraction is used for to address the problem of independent task scheduling in a grid environment, with the aim of reducing the makespan and energy. Experimental results compare ICA with other algorithms and illustrate that ICA finds a shorter makespan and energy relative to the others. Moreover, it converges quickly, finding its optimum solution in less time than the other algorithms.