In this thesis we present two medium access control protocols: Scheduled Power Saving MAC (S-PSM) for Wireless Networks and Minimum Energy and Latency MAC Protocol (MELM) for Wireless Sensor Networks. Scheduled PSM (S-PSM) uses single channel radio mechanism for control and data packets and MELM uses dual channel radio setup named control channel for control packets and data channel for data packets. The S-PSM and the MELM save energy resources and increase network throughput by minimizing packet collisions, overhearing and over transmission. Both S-PSM and MELM eliminates hidden and exposed terminal problem in multi-hop environment. Our simulation result shows that both S-PSM and MELM saves considerable amount of energy.