## 1 Introduction  
Like most Asian countries, Malaysia's economy depends mainly on oil and gas produced from its current reserves [1]. Most of Malaysia's hydrocarbon is produced from its petroleum-bearing sedimentary basins, like those in the onshore West Baram Province of North-west Borneo, Neogene Sandakan Formation of North-east Sabah, and the coal-bearing sequence at Batu Arang, and Western Sabah Basin [2; 3; 4]. Generally, Malaysia's Western Peninsula area has been least explored for hydrocarbons, compared to the Eastern region, however, all possible petroleum yielding areas should be given much attention due to the decline in conventional resources. Also, due to the decline in hydrocarbon production from conventional reservoirs, more focus has been placed on unconventional reservoirs for hydrocarbon generation [5; 6; 7]. Currently, in Malaysia, there is a burning and active desire or aim to explore the potential for hydrocarbon production in the eastern and western Malaysia areas, and to discover new conventional and unconventional hydrocarbon basins. Such studies have mainly focused on the known major sedimentary basins, including Penyu, Malay, Sabah, Sarawak, Sandakan, and some parts of the Tarakan basins [8; 9; 10; 11]. There are several stand-alone studies on the source rock potentials of several basins or formations in east and west Malaysia [8; 9; 12; 13; 14; 15; 16]. However, they all fail to provide a holistic insight into Malaysia's key hydrocarbon generation potential. Therefore, systematic review studies are needed to provide useful state-of-the-art knowledge on the potential of these basins and formations in Malaysia. This would provide new future directions and recommendations toward the discovery of new conventional and unconventional reservoirs. To fully understand the hydrocarbon potential of formations, it is important to characterize them using geochemical techniques [17; 18]. This includes determining the entire amount of organic matter available in the sediments (Source richness), thermal maturity level, and, finally, the type of organic matter (Source quality) [17; 19; 20]. Source richness deals with the amount of organic matter present in the rocks capable of generating hydrocarbons [19]. According to [PERSON] [21], the capacity of a rock to generate hydrocarbons depends heavily on the quantity of organic matter available. It is deemed to be a sign of the sediment's capacity for hydrocarbon generation and not just a measurement of the quantity of organic matter present [19]. Source quality indicates the types of organic matter present in the sediment, giving an idea of the type of hydrocarbons the sediment can generate [19]. As burial depth increases, there is increasing pressure and temperature which cooks the sediments and causes them to lithify and this transforms the organic matter in them to kerogen [22]. Therefore, the thermal maturity parameter indicates the stages of hydrocarbon generation the sediment has undergone [23; 24; 25]. These three main parameters were used to classify the formations analyzed. It is important to combine several analytical techniques for a more precise source rock evaluation [17]. The analytical techniques often used are Total Organic Carbon (TOC) analysis, Rock-Eval Pyrolysis, and Vitrinite Reflectance analysis [17; 25; 26; 27]. This review reports on almost all the articles in the literature on the source rock potentials in the east and west Malaysia, by systematically providing insight and details on the TOC, generic potential (GP), hydrocarbon yield (S2) and vitrinite reflectance (R\({}_{\rm o}\)) of Malaysian formations/basins. For simplicity, the paper categorizes the source rock potential parameters according to the basins' geographical locations: Peninsula, Sabah, and Sarawak. The findings in this article encourage the discovery of new conventional and unconventional hydrocarbon resources in Malaysia. The data provided in review tables could be used for basin hydrocarbon modeling in Malaysia.