Different acid types, hydrochloric acid and acetic acid, were used to prepare collagen solutions. The effects of acid types on physical and biological properties of collagen scaffolds were investigated. The collagen solution prepared with hydrochloric acid (C-HCl) was much more viscous than that prepared with acetic acid (C-Acetic). The conformation of collagen chains was expected to be different due to differences in ionic strength of collagen solutions. Morphology of the scaffolds analyzed by scanning electron microscopy (SEM) revealed that C-HCl scaffolds had larger pore sizes (around 100 microm) than C-Acetic scaffolds (around 50 microm). The more viscous C-HCl solution resulted in harder scaffolds shown by higher compressive modulus. However, the swelling ability of the C-Acetic scaffolds was higher in phosphate-buffered saline solution. The results from in vitro L929 cell culture showed that C-HCl scaffolds could promote cell initial attachment while the C-Acetic scaffolds enhanced cell proliferation. Therefore, the type of acid used as a solvent to form collagen solution affects the morphology, physical and biological properties of the resulting collagen scaffolds.