High filling of single wall carbon nanotubes (SWCNT) with C-60 and C-70 fullerenes from solvent is reported at temperatures as low as 69 degreesC. A 2-h long refluxing in n-hexane of the mixture of the fullerene and SWCNT results in a high yield of C-60,C-70@SWCNT, fullerene peapod, material. The peapod filling is characterized by TEM, Raman and electron energy loss spectroscopy and X-ray scattering. We applied the method to synthesize the temperature sensitive (N@C-60:C-60)@SWCNT as proved by electron spin resonance spectroscopy. The solvent prepared peapod samples can be transformed to double walled nanotubes enabling a high yield and industrially scalable production of DWCNT. (C) 2003 Elsevier B.V. All rights reserved.