NOVELTY - A fuel cell system comprises modules arranged in the vehicle in directions and at distances relative to one another depending on available space in the vehicle, and arranged in a relative orientation that is at least one above one another and side-by-side. The module comprises fuel cell module(s) (3) having a stack of individual cells, an anode module (5) having fuel feeding and fuel removal apparatus, a tank module having a hydrogen storage device, an air module (2) having air feeding and air removal apparatus, moistening module(s) (4), and an electric/electronics module (6).    USE - Fuel cell system for generating electric power for vehicle.    ADVANTAGE - The fuel cell system permits maximal flexibility at minimal expense. It can be integrated in different types of vehicles with slight adaptations.    DETAILED DESCRIPTION - A fuel cell system comprises modules arranged in the vehicle in directions and at distances relative to one another depending on the space available in the vehicle, and arranged in a relative orientation that is at least one above one another and side-by-side. The module comprises fuel cell module(s) (3) having a stack of individual cells, an anode module (5) having fuel feeding and fuel removal apparatus, a tank module having a hydrogen storage device, an air module (2) having air feeding and air removal apparatus, moistening module(s) (4) for moistening air flowing into the fuel cell module, and an electric/electronics module (6). The anode module has an anode gas recirculation device. The electric/electronic module includes elements for transmitting generated power. INDEPENDENT CLAIMS are included for:    (1) a vehicle having the fuel cell system; and    (2) a method of installing a fuel cell system in a vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a plan view of vertical construction of a modular fuel cell system.    Air module (2)    Fuel cell module (3)    Moistening module (4)    Anode module (5)    Electric/electronics module (6)