The maximal operators for Cesàro or (C, ) and Riesz summability with respect to Walsh-Fourier series are investigated as mappings between dyadic Hardy and Lebesgue spaces. It is well known that they are bounded from H p to L p for all 1/( + 1) < p < ∞. In this work we prove that this boundedness result does not hold anymore if p 1/( + 1). However, for p = 1/( + 1) the maximal operators are bounded from H 1/( +1) to the weak L 1/( +1) space. To the proof some known estimations for the Cesàro and Riesz kernels have to be sharpened.