The paper presents the microscopic and mechanoacoustic study of degradation processes of the porcelain material C 130 type. This kind of material is used in the production of the most durable and reliable electrotechnical elements. Raw material composition of the studied porcelain was modified. This had an impact on the inner properties, cohesion and – in consequence – on operational properties of the material. Using mechanical-acoustic and microscopic methods of testing of small-size samples that were subjected to compression, it was possible to distinguish successive stages of degradation of the porcelain structure. These stages were generally typical of the porcelain materials. In the authors’ opinion, they are connected to the ageing process happening over many years of work under operating conditions. Optimization of composition and technological properties – important during technological processes – resulted in a slight decrease in inner cohesion of the porcelain. When compared to the reference material – typical domestic C 130 material, mechanical strength was somewhat lower. Carried out investigations proved that resistance of the investigated material to the ageing degradation process – during long term operation – also decreased. The improvement of technological parameters and the reduction in the number of defective elements occurred simultaneously with some decrease in the operational parameters of the material. To restore their initial high level, further work is needed to optimize the raw material composition of the porcelain.