Due to the wide range of applications, high specific loads, high stresses, and environmental boundary conditions, the materials of marine engines and especially those of outboard marine engines have to fulfill a wide range of requirements. These include high corrosion resistance, high material strength, low specific gravity, high impact loading capability, and lightweight design. Besides the technical properties, these materials must also meet also the manufacturing and cost requirements. The aim of the present article is to compare and contrast the requirements of the marine and automotive industries and give a comprehensive overview of the materials and processes used. Many marine engines are operated with open cooling systems, which means that all parts exposed to the cooling fluid face a wide range of mineral concentration (salts) and debris. Therefore the materials used for these engines are mainly low copper aluminum, stainless steel and engineered structural plastics. To give parts exposed to salt water additional corrosion protection, a strontium chromate-based layer is applied by flushing the parts with a special chemical fluid. As the entire engine drive system (propeller, structural components) are highly loaded, they must withstand the log strike test, which is a equivalent of a crash test in the automative technology. Composition, properties and preferred application of frequently used Al-Alloys (A356.2, XK360, 515.2, 365.1 Silafon t36, 391) are charaterized. The advantages of specialised processing technologies like precision lost foam casting of Al with pressure and high pressure die casting (HPDC) of Al with salt cores are outlined. Typically steels (8620, 4140) and stainless steels (17-4, 15-5, 13-8Mo, 304, 316L) used in marine applications (drive gear, drive shaft) are given. Several specific material trends to fulfill future demands are as follows: 1) increased used of injection molded structural polymers 2) casting processes for low cost SSM hypereutectic Al-Si Alloys with low Cu contect and high toughness cast alloys such as Silafont 36 3) injection over-molding of electronics and fuel system parts with semi-crystalline polymers 4) new coating technologies.