Coal petrological characteristics along the Piedemonte Llanero and the reconstruction of the deposit environment were obtained from macerals and micro-lithotypes analysis since these data provide information about the processes and prevalent conditions during the peat formation. We analyzed seams from Cenomanian to Miocene geological units (Chipaque Formation, Palmichal Group, Arcillas del Limbo Formation, and San Fernando Formation). Coal range decreases gradually from high-volatile C bituminous (HVCB) in the Chipaque Formation to sub-bituminous C in the San Fernando Formation. The coals are enriched in macerals of vitrinite, whereas the liptinite and inertinite concentrations vary according to the stratigraphic position. The micro-lithotypes are bi-maceral and tri-macerals, being the highest concentrations of clarite and vitrinertoliptite. The results of the facies analysis show that the peat in which the coals developed is mainly of arboreal and herbaceous affinity (rich in lignin and cellulose). Peats are ombrotrophic (rainfed) to mesotrophic (transitional or mixed mires) with variations in the flooding surface and influxes of brackish water. Good tissue preservation is inferred from the wet conditions in forest swamps with few humification and gelation. According to the micro-lithotypes composition, the peat environment was deduced as estuarine system, evolving to lacustrine environment of the deltaic system, both restricted by changes in sea level, which are evidenced by oxic and anoxic periods in the analyzed sequence.