We report a study of single crystal Ca 3 Ir 4 Sn 13 (CIS) and Sr 3 Ir 4 Sn 13 (SIS) by measuring the longitudinal and Hall resistivities, upper and lower critical fields and magnetoresistance, as well as the magnetization. The sign change in the Hall coefficient observed on both the CIS and SIS provides direct evidence for the Fermi surface reconstructing during the superlattice phase transition. Both materials are of current interest due to indications of superconductivity associated with charge-density-wave (CDW) ordering. Observations of the diamagnetic feature and the lower critical field H c1 (T) in both CIS and SIS can be realized by means of the nodeless single-gap BCS theory. In addition, a weak electronic correlation in both systems has been revealed by the small values of the spin exchange energy, upper critical field and Δ(0)/k B T c ratio, derived respectively from the normal-state Hall effect, resistive transition and temperature-dependent H c1 . It is noticeable that the magnetoresistance of SIS shows a rapid increase below T′ ∼ 40 K, following Kohler's scaling rule. The results of the magnetic susceptibility and Hall coefficient also exhibit anomalous features near T′. With respect to these observations, this suggests that the existence of an additional phonon mode with energy of about 4.0 meV in SIS is responsible for the presence of lattice instability toward a phase transition. Ca) 3 Ir 4 Sn 13 results in the suppression of the anomaly to T* ∼ 33 K in Ca 3 Ir 4 Sn 13 (CIS) and the enhancement of the superconducting transition to T c = 7 K [1]. With various measurements, both CIS and SIS have been recognized as BCS-type superconductors with the nodeless s-wave superconducting gaps [5−7]. Specific heat studies have yielded ΔC e /γT c values of 2.09 and 2.78 for SIS and CIS single crystals, respectively [5,8]; where C e is the electronic specific heat, and γ is the electronic specific heat coefficient (Sommerfeld constant). In addition, the specific heat and spin rotation measurements have also derived Δ(0)/k B T c values of 2.04 and ∼5 for SIS and CIS, respectively [5,9], where Δ(0) is the superconducting energy gap at zero temperature. Since these obtained values are relatively larger than those of ΔC e /γT c = 1.43 and Δ(0)/k B T c = 1.76, expected from the BCS theory, both materials have been categorized as strong-coupling superconductors. However, a small ratio of the superconducting transition temperature to normalized Fermi temperature T c /T F of ∼0.001 revealed from the Seebeck coefficient measurement on CIS single crystals implies a weakly electronic correlation in CIS [10]. Also, the contradictory results have been observed through the magnetization measurements on CIS. Wang and Petrovic [10] showed weak diamagnetic behavior for CIS in the normal state, while Yang et al [8] noticed a broad peak feature in the magnetic susceptibility and associated the observation with the coexistence of the superconductivity and ferromagnetic spin fluctuation in CIS. In addition to reexamining the magnet...