Hydro-pneumatic suspension systems consist of two fluids acting upon each other, usually gas over oil. In these systems, a compressible gas such as nitrogen is used as the springing medium, while a hydraulic fluid is used to convert the pressure to force. One of the problems associated with hydro-pneumatic systems is the effect of temperature change on the spring characteristics, which results in a variation in the spring rate and ride height. The important characteristics of a gas chamber filled with gas or air are to maintain the setting pressure, with very small variations, even for long strokes. This paper presents a magneto-rheological (MR) accumulator that can adjust the pressure of the gas chamber through the use of an MR device. To analyze the characteristics of the gas chamber, mathematical modeling based on the energy equation for a gas in a closed container is carried out. Further, a prototype of the MR device is designed and manufactured, and its performance is evaluated. The theoretical results are validated by conducting experiments in the laboratory environment. It is demonstrated that the MR accumulator can effectively compensate for the pressure variations caused by an increase in the gas temperature. Moreover, this research provides new information about the applicability of the MR accumulator to devices that use conventional accumulators.