This is an open label phase I study, to assess the safety of a novel malaria vaccine, AdCh63 CS, simian adenovirus encoding Plasmodium falciparum liver stage antigen, Circumsporozoite protein. All volunteers recruited will be healthy adults. They will be primed with various doses of AdCh63 CS administered intramuscularly. Some of the volunteers will receive a booster vaccination with MVA CS administered via intramuscular route. Safety data will be collected for each vaccination regimen. Secondary aim of this study will be to assess the immune responses generated by vaccination.