The successful realization of devices based on two-dimensional (2D) photonic crystal structures relies on an accurate characterization of the properties of the fabricated nanostructured surface. Scanning electron microscope (SEM) images allow the verification of geometric parameters of fabricated 2D-photonic crystal structures such as the periodicity or the hole diameter. In order to investigate the optical properties of 2D-photonic crystals we realized an experimental setup for spectrally and spatially resolved transmission measurements at normal incidence. These measurements reveal the allowed modes of the photonic crystal at the Gamma-point. In contrast to transmission measurements in the plane of the photonic crystal, these measurements are independent of the lateral termination of the structure, since only the area of the photonic crystal is probed. The experimental setup allows for the characterization of microscopic structures of dimensions down to 50 micrometers in diameter. The setup can furthermore be utilized to characterize the spatial homogeneity of larger nanostructured surfaces. We present experimental results and compare them to photonic band structure calculations.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.