In this paper a high-temperature polydimethylsiloxane (HT-PDMS) flexible substrate is fabricated and surface engineering of it for flexible electronic applications is reported. The reported HT-PDMS has quality properties such as high thermal stability up to 400 °C, high mechanical stability, and high transparency. The reported HT-PDMS was hydrophobic in nature and to change it to hydrophilic, various surface modification treatments are being carried out. The combined treatment of oxygen-plasma and SDS has the ability to change the surface of HT-PDMS to hydrophilic perpetually. The reported HT-PDMS substrate supports a high-temperature fabrication process and has potential applications in flexible optoelectronic devices. © 2022 Elsevier B.V.