For MLCCs operating at temperatures of 150°C or above, such as in automotive electronics and power electronics, a robust dielectric material is necessary. In traditional X8R products (EIA specification, ΔC/C within ±15% between -55°C and +150°C compared that at 25°C), the dielectric material is designed for applications up to 150°C. However, at temperatures above 150°C, these typically suffer from degradation of reliability performance and severe reduction in capacitance, especially under DC bias conditions. Recently, a Ni-electrode based Class-I dielectric has been developed for high temperature application up to 200°C. Due to its linear dielectric nature, this material exhibits highly stable capacitance as a function of temperature and voltage while still maintaining good reliability. MLCCs made from this material can be qualified as X9G. This paper will report electrical properties and reliability test data on these Class-I type ceramic capacitors at temperatures ≥ 150°C. In addition, test data from D-E curves to energy density will be reported along with a discussion of possible mechanisms behind the robust reliability of this material.