An experimental study of two real multi-hole Diesel injectors is performed under current DI Diesel engine operating conditions. The aim of the investigation is to study the influence of injector technology on the flow at the nozzle exit and to analyse its effect on the spray in evaporative conditions and combustion development. The injectors used are two of the most common technologies used nowadays: solenoid and piezoelectric. The nozzles for both injectors are very similar since the objective of the work is the understanding of the influence of the injector technology on spray characteristics for a given nozzle geometry. In the first part of the study, experimental measurements of hydraulic characterization have been analyzed for both systems. Analysis of spray behaviour in evaporative conditions and combustion development will be carried out in the second part of the work. Important differences between both injectors have been observed, especially in their transient opening and closing of the needle, leading to a more efficient air-fuel mixing and combustion processes for the piezoelectric actuated injector. © 2010 Elsevier Ltd. ; Generalitat Valenciana [GV/2009/031] ; Payri Marín, R.; Salvador Rubio, FJ.; Gimeno García, J.; Morena Borja, JDL. (2011). Influence of injector technology on injection and combustion development, Part 1: Hydraulic characterization. Applied Energy. 88(4):1068-1074. doi:10.1016/j.apenergy.2010.10.012. ; Senia ; 1068 ; 1074 ; 88 ; 4