A b s t r a c t Power system operation with proper planning is an utmost task for enhancing the economy of the country. The Optimal Reactive Power Dispatch (ORPD) plays an important task for secure, reliable and optimal operations of power system. ORPD is a complex, non-linear, non-convex, non-continuous and multi-model problem which involves discrete as well as continuous variables. Thus, its solution comprises of different objective functions like improving voltage profile, reducing power losses, voltage stability enhancement and transmission cost minimization. Due to the non-linear nature of problem, most of the techniques applied to ORPD are meta-heuristic. Despite the numerous articles published on these techniques, none has given sufficient emphasis on the comprehensively summarizing the existing meta-heuristic methods for solution of ORPD problem. This work presents a survey of different meta-heuristic techniques applied for solution of ORPD problems in power transmission system. Moreover, a new meta-heuristic Sine-Cosine algorithm is also proposed to solve the problem. A case study is performed where different meta-heuristic techniques are implemented to solve the same problem. Later, statistical analysis is performed to rank all implemented techniques. It is envisaged that the information gathered in this paper will be a valuable one-stop source of information for researchers working on this topic.