This paper presents some quantitative measurements of the adhesion energy of thin WTi films deposited on Si substrate. Two different techniques are applied to the same sample series. One is a mechanical test based on the analysis of spontaneously formed defects. The second is based on acoustic waves whose reflection at the interface between the thin-film and the substrate is sensitive to the adhesion. An excellent correlation is obtained between both approaches: the adhesion energy measured by buckles analysis and acoustic reflection coefficient measured by picosecond acoustics. The acoustic approach offers several advantages among which a non-destructive character, a compatibility with complex stacks and a sensitivity to detect adhesion anomaly even if no defect is formed.