Vertically aligning carbon nanotubes (VACNTs) onto 2D porous materials is advantageous for many conceivable electronic applications but also for investigating the unique water transport properties of CNTs and the molecular separation of molecules during fluid transport through their inner shell. Here we report a wet chemical technique to produce vertically-aligned single walled CNT arrays on porous silicon (pSi). The nanotubes were first acid treated to produce carboxylic acid functionalities on the single-walled CNT. The carboxy-functional nanotubes were then covalently immobilised on a pSi surface that had been either ozone treated or silanated with aminopropyl triethoxysilane (APTES). The VACNT surfaces were analysed with atomic force microscopy (AFM), confocal Raman spectral imaging and Fourier transform infrared (FTIR) spectroscopy. Dense arrays of VACNTs were observed with the obtained CNT orientation and surface coverage depending upon attachment method and attachment reaction time.